Tantalum Capacitors – Solid Leaded

23. March 2020 10:35 by Admin in Tantalum Capacitors Blog

A tantalum electrolytic capacitor is one of the passive components of an electronic circuit. It comprises of a pellet of permeable metals of tantalum (anode) which is covered all around by an insulating oxide layer forming the dielectric. It is covered solid or even liquid electrolytes (cathode). The tantalum capacitor has a very thin and comparatively high permittivity dielectric layer and because of this, it is much better than other capacitors in having high Capacitance/Volume as well as lower weight.

Tantalum is known to be a conflict mineral. The Tantalum Electrolytic Capacitors are found to be more costly than the Aluminum Electrolytic Capacitors.

Tantalum capacitors are intrinsically polarized segments. If the reverse voltage is applied then the capacitors may get destroyed. Bipolar or Non-polar Tantalum Capacitors can be made by adequately interfacing two capacitors which are polarized in series, with the anode having an orientation in the opposite direction.

 

Basic Construction of Solid Tantalum Electrolytic Capacitors

A Tantalum Capacitor is basically a chip capacitor which consists of tantalum powder pressed and compacted into a pellet and forms the anode of the capacitors. The oxide layer of tantalum pentoxide forms the dielectric and the cathode is a solid manganese dioxide electrolyte.

 

                                                                                                        

Types of Tantalum Capacitors

The Tantalum Electrolytic Capacitors are made up in 3 different styles:

  • Axial Leaded Tantalum Capacitors – This kind of capacitor is generally used in medical, space and military applications.
  • Tantalum “pearls” single-ended style (resin-dipped) used for PCB mounting.
  • Tantalum Chip Capacitors – It has an SMD style and is used for surface mounting. Eighty percent of all Tantalum Capacitors are SMDs.

 

Chip Capacitors

As said above, more than eighty percent of Tantalum Electrolytic Capacitors are made in SMD style as Tantalum Chip Capacitors. The end faces consist of contact surfaces, furthermore, is fabricated in various sizes. One can identify different sizes using case code letters. For some of them which have been fabricated for a long time, the measurements and case coding overall makes are still to a great extent equivalent. But due to the new features of Tantalum Electrolytic Capacitors, like the “face down” technique to decrease inductance and the multi-anode technique to decrease the ESR has resulted in a much broader range of chip sizes and case codes. These takeoffs from EIA benchmarks mean gadgets from various producers are never again constantly uniform.

 

Wet Tantalum Capacitors

One of the main characteristics of the modern days Wet (non-solid) Tantalum Electrolytic Capacitor is the energy density they have as compared to the Wet Aluminum Electrolytic Capacitors and Solid Tantalum Capacitors. The self-healing property in them enables the formation of dielectric thickness with a much lower safety margin. In addition to that, Wet Tantalum Capacitors can be operated at an excess voltage from 100 V to 630 V. Apart from that it has the lowest leakage current and a relatively low ESR than all other electrolytic capacitors.

 

Hope you liked the article on Tantalum Capacitors. Brands that manufacture these types of capacitors are Kemet, Vishay, and AVX. Make sure to check them out using the links as provided.

Multilayer Ceramic Capacitors MLCC – Leaded

A ceramic capacitor is regarded as the fixed value capacitor where the dielectric is a ceramic material. It is made up of alternating 2 or more layers of ceramic as well as a layer of metal that behaves like an electrode. The piece of the ceramic material characterizes electrical conduct and consequently applications. Ceramic capacitors can be categorized into 2 application classes:

  • Class 1 Ceramic Capacitors – This type of ceramic capacitors provide low losses and high stability for resonant circuit applications.
  • Class 2 Ceramic Capacitors – It provides high volumetric efficiency for coupling, by-pass, and buffer applications.

Ceramic capacitors mostly the Multilayer Ceramic Capacitors - MLCC are one of that electrical equipment that is the most used ones. They are available in different sizes and shapes and are utilized in capacitors for EMI / RFI suppression, power capacitors for transmitters and as feed-through capacitors.

 

MLCC

An MLCC or Multi-Layered Ceramic Capacitors comes with several separate capacitors that are grouped together in parallel and are contacted using the terminal surface. The materials used for making MLCC chips are a mixture of ferroelectric or paraelectric (finely ground granules) with some precisely decided added substances. Both of them are mixed together to form a homogeneous mixture. The size of the powder as well as the composition of the mixture (small as 10nm) shows the expertise of the manufacturer.

                                                            

A thin foil of ceramic is cast from a suspension of the powder with an appropriate binder. This ceramic foil is then rolled up for transport. It is then unrolled. After this, they are divided into sheets of equal size which are screen printed using a paste of metal. Now, these sheets are our electrodes. These sheets are grouped together in layers and pressure is applied which can be solidified on the application of pressure in an automated process. Along with the relative permittivity, the number and size of the layers help in deciding the value of capacitance. The electrodes are grouped in an alternate arrangement somewhat balanced from the abutting layers with the goal that they each can later be associated on the offset side, one right, one left. The stack that is layered is cut into small individual components. High mechanical exactness is required.

After the cutting process is over, the binder is worn out of the stack. This is trailed by sintering at temperatures somewhere in the range of 1,200 and 1,450 °C creating the last, essentially crystalline, structure. The burning process then makes up the needed dielectric properties. Cleaning and metallization are succeeded in the burning process. With the help of the metallization process, the inner and the ends electrodes get connected in parallel and the terminal is provided to the capacitor. At last, a 100% estimating of the electrical qualities will be finished.

                         

This was all we have regarding MLCC. Hope you liked going through it. Brands that manufacture them are Kemet, AVX and TDK. Make sure to follow them using the links as provided. Thanks for reading.

Aluminum Electrolytic Capacitors - Leaded

23. December 2019 12:25 by Admin in Aluminum Electrolytic Capacitors Blog

An aluminum electrolytic capacitors come under the category of electrolytic capacitors that are polarized and whose anode electrode is made using an aluminum foil (pure) with an etched surface. A very thin layer of aluminum oxide is formed by aluminum. It behaves as the dielectric of the capacitor. The electrolyte (non-solid) which covers up the rough surface of the layer of the oxide, serves as the cathode of the capacitor. "Cathode foil" which is the second aluminum foil contacts the electrolyte and fills in as the electrical association with the negative terminal of the capacitor.

The aluminum electrolytic capacitors can be divided into 3 subfamilies based on kind of electrolyte:

  • Liquid, wet or non-solid aluminum electrolytic capacitors,
  • Solid polymer aluminum electrolytic capacitors,
  • Solid Manganese dioxide aluminum electrolytic capacitors.

Aluminum electrolytic capacitors that come under the non-solid electrolyte is regarded as one of the most inexpensive types of capacitors coming with a wide range of capacitance, voltage values, and sizes. They can be found with capacitance value ranging from 0.1 µF up to 2,700,000 µF with a voltage rating value from 4V to 630V. The liquid electrolyte offers oxygen for self-heating or re-forming of the layer of dielectric oxide. Though, it can vanish through a temperature-subordinate drying-out procedure, which makes electrical parameters drift, restricting the lifetime of service as provided by the capacitors.

The aluminum electrolytic capacitor has a high capacitance value which enables it to offer low impedance value at lower frequencies lie that at mains frequency. They are popularly used in switched-mode power supplies and DC-DC converters for buffering and smoothing redressed DC voltages in numerous electronic gadgets. It is also used as inverters for photovoltaic, DC link capacitors for drivers, and converters in wind power plants. Some of its special kinds are utilized in the storage of energy, i.e. in strobe or photoflash applications. In addition to that, it also serves in audio applications for frequency coupling.

Because of their anodization principal, the aluminum electrolytic capacitors are polarized capacitors. They can be managed with the DC voltage when applied with the right polarity. When the capacitor is being operated using an AC voltage or with the wrong polarity then it may result in a short circuit and can harm the device. The only exceptions are the use of a bipolar aluminum electrolyte capacitor. It has a consecutive arrangement of two anodes in a single case and can be utilized in AC applications.

 

Advantages:

  • Diversification in series, styles, electrical parameters and temperature.
  • High energy density than ceramic capacitors and film capacitors.
  • No limitation for peak current required.
  • It has a high power density than supercapacitors.

 

Disadvantages:

  • Polarized application.
  • It is sensitive to mechanical stress.
  • It is sensitive to contamination with halogens.

 

This was all we have regarding aluminum electrolyte capacitors – Leaded. Hope you liked going through it. Brands that manufacture them are Nichicon, Panasonic and United Chemicon. Make sure to check them out using the links as provided.

Ceramic Disc Capacitors

23. December 2019 12:20 by Admin in Ceramic Disc Capacitor - Blog

A ceramic capacitor is regarded as the fixed value capacitor where the dielectric is a ceramic material. It is made up of alternating 2 or more layers of ceramic as well as a layer of metal that behaves like an electrode. The piece of the ceramic material characterizes electrical conduct and consequently applications. Ceramic capacitors can be categorized into 2 application classes:

  • Class 1 Ceramic Capacitors – This type of ceramic capacitors provide low losses and high stability for resonant circuit applications.
  • Class 2 Ceramic Capacitors – It provides high volumetric efficiency for coupling, by-pass, and buffer applications.

Ceramic capacitors are one of that electrical equipment that is the most used ones. They are available in different sizes and shapes and are utilized in capacitors for EMI / RFI suppression, power capacitors for transmitters and as feed-through capacitors.

 

Application Classes – Definitions

The distinctive ceramic materials utilized for making ceramic capacitors like ferroelectric or paraelectric ceramics impacts the electrical attributes of the capacitors. Utilizing the mixture of paraelectric substance that is in light of titanium dioxide brings about entirely steady and linear capacitance value within a pre-defined range of temperature and low losses at high frequencies. The mixture as said above has a low value of permittivity such that the capacitance of these capacitors is generally less.

To get a high value of capacitance in ceramic capacitors, a mixture of ferroelectric materials, like barium titanate, and its specific oxides should be used. The permittivity value of this dielectric material is much higher but the capacitance is non-linear over the range of temperature, and the loss at high frequency is much higher. These features of ceramic capacitors need to be grouped into "application classes". Let's have a look at each of them.

  • Class 1 Ceramic Capacitors – Class 1 Ceramic Capacitors are much accurate and temperature-redressing capacitors. They provide the most steady and stable temperature, voltage as well as frequency to some extent. Because they have low losses, they are generally suitable for resonant circuit applications. The fundamental materials required for making Class 1 Ceramic Capacitors consist of paraelectric materials (finely ground granules) like TiO2 (Titanium Dioxide) altered by added substances of Zirconium, Tantalum, Niobium, Zinc, Strontium, Cobalt and Magnesium. All of these are important to get the desired linear characteristics of the capacitors.

 

  • Class 2 Ceramic Capacitors – Class 2 Ceramic Capacitors have a high permittivity along with a dielectric and because of this, it has a much better volumetric efficiency than Class 1 Capacitors. But still, it has lower stability and accuracy than the Class 1 Capacitors. The ceramic dielectric is described by a nonlinear difference in capacitance over the temperature run. The capacitance value of the capacitor also relies on the applied voltage. They are good for coupling, decoupling and bypass applications.

 

This was all we have regarding Ceramic Disc capacitors. Hope you liked going through the article. Brands that manufacture them are Vishay, Murata, and TDK. Make sure to follow them using the links as provided.

Infrared Emitters

20. December 2019 08:41 by Admin in Infrared Emitters - Blog

Infrared radiations or infrared light are that category of electromagnetic radiations whose wavelength is longer than that of visible light. Thus these radiations can't be seen through human eyes. Most of the thermal radiation which is radiated by materials present at room temperature is infrared. Like all other electromagnetic radiation, infrared radiations also come with radiant energy and carry on both like a quantum particle (photon) as well as a wave

Infrared radiation was founded by Sir William Herschel in 1800. It was also known that marginally the greater part of the total vitality from the Sun was inevitably found to land on Earth as infrared. The balance between emitted and absorbed infrared radiation critically affects Earth's atmosphere.

Infrared radiation has found its use in scientific, law enforcement, industrial, medical, and military applications. The gadgets with night vision that utilizes dynamic close infrared brightening offer animals and people to be seen without the observer being recognized. The thermal imaging cameras having an infrared feature helps in finding out the loss of heat in insulated systems, to know which electrical equipment is getting overheated as well as to watch changing bloodstream in the skin. Civilians and military use infrared radiations for night vision, tracking, homing, surveillance and target acquisition.

The transmission of infrared radiation is possible only because of 2 components. One is the infrared emitter and the other one is the infrared receiver. This blog is all about Infrared Emitter. So let’s move forward for it.

 

Infrared Emitters

A clear line of sight is required for an infrared signal in order to work. If you are turning the face of an infrared remote control in the direction opposite to that of the equipment that needs to receive its signal then there is a high possibility that nothing is going to happen. The transmission of the signal is not going to be an effective one. To solve the above-mentioned problem, all the infrared system utilizes local infrared emitters. Basically, an infrared emitter is referred to as a remote control that is located in front of the gadget that you are using. It is associated with our control framework by a wire.

 

Placement of Infrared Emitter

You must place the infrared emitter on the front side of the gadget that you want to operate. It is also advisable to keep your infrared emitter just above the infrared receiver to support reliable functioning. If you are not able to get the exact location of your infrared receiver then you need to move the infrared emitter around while testing the remote to locate the best possible spot to mount it.

The acceptance signal is interfered due to strong sunlight. If you are placing it at a position with mini-mum exposure to sunlight, you will get the best result. When you are summing up to more than one infrared emitter to the infrared output, the strength of the infrared signal gets decreased with each addition. Thus, you must place infrared emitter at its proper spot.

This was all we have regarding Infrared Emitters. Hope you enjoyed going through the article. Brands that manufacture them are Everlight, Vishay and TT Electronics. Make sure to visit them using the links as provided. Thanks for reading.

Fiber Optic Cable

20. December 2019 08:36 by Admin in Fiber Optic Cables - Blog

An optical fiber cable or a fiber optic cable is much similar to an electrical cable but comes with optical fibers that can carry light. The elements of optical fiber are typically layered with plastic and are contained inside a protective tube suitable for the surroundings where the cable will be utilized. There are various kinds of cables used for various applications, for instance, offering connectivity of high speed of data, long-distance telecommunication, etc.

Different cable types are as follows:

  • MDU: Fiber optics cable, multiple dwelling unit
  • OSP: Fiber optic cable, outside plant
  • ADSS: All-Dielectric Self-Supporting
  • OPGW: Optical fiber composite overhead ground wire
  • OFNR: Optical fiber, nonconductive, riser
  • OFCR: Optical fiber, conductive, riser
  • OFNP: Optical fiber, nonconductive, plenum
  • OFCP: Optical fiber, conductive, plenum
  • OFNG: Optical fiber, nonconductive, general use
  • OFCG: Optical fiber, conductive, general use
  • OFN: Optical fiber, nonconductive
  • OFC: Optical fiber, conductive

 

Reliability and Quality

Optical fibers are known to be extremely strong but its quality is radically decreased by unavoidable infinitesimal surface blemishes characteristic in the assembling procedure. The change of fiber with time along with initial strength must be viewed as comparative with the pressure forced on the fiber during its installation, cabling, and handling for some given environmental conditions. There are a total of 3 fundamental scenarios that can result in the degradation of strength, they are:

  • Dynamic fatigue
  • Zero-stress aging
  • Static fatigues

 

Cord jacket color coding

  • Orange – Multi-Mode Optical fiber.
  • Aqua - OM3 or OM4 10 G laser-optimized 50/125 µm multi-mode optical fiber.
  • Erika Violet - OM4 multi-mode optical fiber.
  • Lime green - OM5 10 G wideband 50/125 µm multi-mode optical fiber
  • Yellow – Single-Mode Optical fiber
  • Blue – Used sometimes to identify polarization-maintaining optical fiber.

 

Jack Material 

The jacket material is application-explicit. The material helps in getting accustomed to the chemical, resistance from Ultra Violet radiations, mechanical robustness, etc. Some of the popular materials used for jackets are polyvinyl chloride, LSZH, polyethylene, polybutylene terephthalate, polyurethane, and polyamide.

 

Fiber Material

Two of the most common material utilized in making optical fibers are plastic and glass. They provide generally various qualities and are utilized in altogether different applications. The plastic fiber is utilized if the need is for a consumer application or a short-range. On the other hand, the glass fiber is utilized for long-range (Single Mode) as well as short-medium range (Multi-Mode) telecommunications.

 

Propagation speed and delay

The transferring speed of data in optical cables is that of the speed of light in the glass. This is equal to the speed of light present in the vacuum divide by the glass's refractive index. It comes around to be 180k to 200k kilometer per second, bringing about 5.0 to 5.5 microseconds of inertness per km. Thus, 11 milliseconds is the round trip delay time for a thousand kilometer.

 

This was all we have regarding fiber optics cable. Hope you liked reading it. Brands that manufacture them are Panduit and Avago. Make sure to follow them using the links as provided.

Infrared Receiver

20. December 2019 08:34 by Admin in Infrared Receivers - Blog

Infrared radiations or infrared light are the categories of electromagnetic radiations whose wavelength is longer than that of visible light. Thus these radiations can't be seen through human eyes. Most of the thermal radiation which is radiated by materials present at room temperature is infrared. Like all other electromagnetic radiation, infrared radiations also come with radiant energy and carry on both like a quantum particle (photon) as well as a wave.

Infrared radiation was founded by Sir William Herschel in 1800. It was also known that marginally the greater part of the total vitality from the Sun was inevitably found to land on Earth as infrared. The balance between emitted and absorbed infrared radiation critically affects Earth's atmosphere.

Infrared radiation is absorbed and emitted by molecules when their vibrational and rotational movements are changed. Because of the change in the dipole moment, the vibrational modes in a molecule gets excited, making it a valuable recurrence run for investigation of these vitality states for atoms of the best possible evenness. Infrared spectroscopy helps in examining the transmission and absorption of photons in the range of the infrared spectrum.

Infrared radiation has found its use in scientific, law enforcement, industrial, medical, and military applications. The gadgets with night vision that utilizes dynamic close infrared brightening offer animals and people to be seen without the observer being recognized. The thermal imaging cameras having an infrared feature helps in finding out the loss of heat in insulated systems, to know which electrical equipment is getting overheated as well as to watch changing bloodstream in the skin. Infrared astronomy utilizes telescopes equipped with sensors to get into dusty regions present in space like the molecular clouds, find out substances like planets, and to get a good view of highly red-shifted objects from the initial days of the galaxy. Civilians and military use infrared radiations for night vision, tracking, homing, surveillance and target acquisition.

The transmission of infrared radiation is possible only because of 2 components. One is the infrared emitter and the other one is the infrared receiver. This blog is all about Infrared Receiver. So let’s move forward for it.

 

Infrared Receiver

A clear line of sight is required for an infrared signal to work. If you are turning the face of an infrared remote control in the direction opposite to that of the equipment that needs to receive its signal then there is a high possibility that nothing is going to happen. The transmission of the signal is not going to be an effective one. To solve the above-mentioned problem, all the infrared system utilizes local infrared emitters. An infrared emitter is referred to as a remote control that is located in front of the gadget that you are using. It is associated with our control framework by a wire.

It is important to have an infrared receiver along with an infrared emitter. An infrared radiation receiver or an infrared receiver is hardware that helps in sending information to some other device from an infrared remote control by decoding and receiving the signals. It is advisable to keep your infrared receiver just below the infrared receiver to support reliable functioning.

This was all we have regarding the infrared receiver. Brands that manufacture them are Everlight, Vishay and Sharp. Make sure to visit them using the links as provided.

Laser Diode

20. December 2019 08:29 by Admin in Laser Diode - Blog

An Injection Laser Diode (ILD) or a Laser Diode (LD) or a Diode Laser is a semiconductor that is much similar to that of an LED (Light Emitting Diode) where a diode siphoned legitimately with electrical current can lead to a lasing condition at the junction of a diode. Laser diodes can convert electrical energy directly into light. Initiated by a potential difference, the doped P-N transition offers joining of the electron with a hole (positive space). As the electron gets dropped to a low energy level from a high energy level, radiations are emitted in the form of photons. This is an example of spontaneous emission. Whenever the procedure is continued, stimulated emission can be generated.

The type of material used as semiconductors helps in determining the emitted beam's wavelength. Laser diodes that we use today range from ultraviolet to infrared spectrum. Laser diodes are the most well-known type of lasers created, with a wide scope of utilization that incorporates barcode readers, CD / DVD / Blu-ray disc recording/reading, optic communications, laser pointers, laser printing, light beam illumination, and laser scanning. Laser diodes can be utilized for general illumination with the help of phosphor (found in white LEDs).

 

Theory of Operation

A laser diode is electrically referred to as a PIN diode. The laser diode comes with the active region in the intrinsic (I) region, and the holes, as well as the electrons, are pushed into that region from the P and the N regions respectively. One of the very first studies on diode laser was carried out on simple P-N diodes. Today all lasers utilize the Double Hetero Structure implementation. Here the photons and the carriers are restricted so as to expand their odds for recombination and generation of light. In contrast to the regular diode, the main aim of a laser diode is to join up all the carriers in the intrinsic region and generate light. Therefore, laser diodes are created utilizing Direct Band Gap semiconductors. The epitaxial structure of a laser diode is formed by utilizing the technique of crystal growth, generally initiating from the N-doped layer and building up the intrinsic doped active layer, succeeded by the P-doped cladding, and a contact layer. Most often, the active layer comes with quantum wells that offer higher efficiency and lower threshold current.

 

Applications

  • Medical uses – In the field of medical science, especially that of dentistry have discovered several uses of diode lasers. It's small size and cheap cost along with user-friendliness make it very much alluring to clinicians for minor delicate tissue strategies.

 

  • Telecommunications, Spectrometry, and scanning – Laser diodes are used much widely in telecommunication as easily coupled and modulated light sources for carrying out fiber optics communication. It has also found its use in barcode readers. Visible lasers (generally red and green) are also very much popular as laser pointers.

 

This was all we have regarding laser diodes. Hope you enjoyed going through it. Brands that manufacture them are Finisar, OSRAM and TT Electronics. Make sure to follow them using the links as provided.

Standard LEDs – Through Hole

20. December 2019 08:25 by Admin in Standard LEDs - Through Holes - Blog

LED is a light-producing semiconductor which discharges light when electric current moves through it. The electrons present in the semiconductor get attached with electron holes and release photons (energy). The shade of the light is dictated by the vitality required for electrons to overcome the bandgap of the semiconductor. White light can be generated by a film of a light-emitting phosphor on the device.

The earliest LEDs, which was developed in around 1962, used to emit infrared lights of low intensity. Infrared LEDs have found its use mostly in remote control circuits which can be found in equipment linked with consumer electronics. Modern LEDs come with ultraviolet, infrared and visible wavelengths with the high light output.

LEDs have several advantages over an incandescent light. They are:

  • Long Lifetime
  • Small Size
  • Fast switching
  • Improved physical robustness

LEDs have found its use in automotive headlamps, traffic signals, plant growing light, aviation light, medical devices, lighted wallpaper, camera flashes, plant growing light, and advertising.

In contrast with a laser, the light that is released from an LED is neither highly monochromatic nor spectrally coherent. Still, its spectrum is adequately narrow that it can be recognized by the human eye as a saturated color.

 

Standard LEDs – Through Hole

LEDs are available in several different sizes and shapes. The category of LEDs that you will be using most is the through-hole LEDs with 2 legs. There are multiple LEDs that are hard and small to solder but these are simple and easy to use along with a breadboard provided that are available with long wires you can stick in. The light emitter is defended by a clear bulb. Consistently, through-hole LEDs have overwhelmed the market of high-brilliance LEDs, in light of their exceptionally intelligent structure with essential optics.

LED lamps or through-hole LEDs have mostly found its use in outdoor applications as they provide multiple benefits over standard surface mount (SMT) LEDs. Let's have a look at some of the characteristic feature of Through-Hole LEDs:

  • They are brighter.
  • They are very clear.
  • They are available either as tint-diffused or tinted for higher contrast ratios.
  • They have a diverse range of essential optic design.

Due to the availability of primary optics, LED lamps or through-hole LEDs are considered as one of the best choices regarding definition, brightness, and controlled viewing angles.

This was all we have regarding through-hole LEDs. Hope you enjoyed going through the blog. Brands that manufacture them are Everlight, Lumex, and Kingbright. Make sure to follow them using the links as provided. Thank you for reading.

Photodiodes

20. December 2019 08:20 by Admin in Photodiode - Blog

A photodiode is referred to that semiconductor equipment that transforms light into an electric current. The electric current is formed when photons get absorbed in photodiodes. This electrical equipment may consist of built-in lenses, optical filters, with small and large surface areas. One of the commonly and traditionally used solar cells known as electric solar power is an example of a large area photodiode.

Photodiodes are much similar to regularly used semiconductor diodes but they might be either uncovered or covered with an optical fiber connection or window to enable light to come and hit some of the sensitive device’s parts. To uplift the response of speed, several diodes intended for use as a photodiode utilizes a PIN junction in place of a P-N junction. A photodiode is designed basically to work in reverse bias.

 

Principle of Operation

As said earlier, a photodiode is a PIN structure or a P-N junction. Whenever a photon containing enough energy hits the diode, it forms an electron-hole pair. This process is called the photoelectric effect. If the assimilation happens in the depletion region of the junction, or one dispersion length away from it, these electron and holes are cleared from the junction by the electric field generated inside the depletion region. Thus the electrons go towards the cathode while the holes move toward the anode, producing a photocurrent. The net amount of current passing through the photodiode is equal to the sum of the dark current (current formed in the absence of light) and the photocurrent. Thus to get a maximum value of the device’s sensitivity, the dark current should be minimized.

 

Materials

The materials that can be utilized to create a photodiode is the basic to characterize its properties because only photons that are having enough energy to excite electrons across the bandgap of the material will generate notable photocurrents.

Materials that are used popularly to make photodiodes are:-

  • Silicon – Range of electromagnetic spectrum wavelength is from 190nm to 1100nm.
  • Germanium - Range of electromagnetic spectrum wavelength is from 400nm to 1700nm.
  • Indium gallium arsenide - Range of electromagnetic spectrum wavelength is from 800nm to 2600nm.
  • Lead (II) sulfide - Range of electromagnetic spectrum wavelength is from <1000nm to 3500nm.
  • Mercury cadmium telluride - Range of electromagnetic spectrum wavelength is from 400nm to 14000nm.

The noise generated by silicon-based photodiodes is less as compared with the germanium-based photodiodes. The reason behind this is that they have greater bandgaps.

 

Comparison with Photomultipliers

A photomultiplier is a device that can generate an electrical signal from the incident photons.

Advantages of photodiodes over photomultipliers:

  • Low noise.
  • Light in weight and compact.
  • It has a longer lifetime.
  • High voltage is not needed.
  • Quantum efficiency is high.

 

Disadvantages of photodiodes over photomultipliers:

  • The area is small.
  • Response time is slower.
  • Overall sensitivity is much low.

This was all we have regarding photodiodes. Hope you enjoyed going through it. Brands that manufacture them are Osram, First Sensor, and Vishay. Make sure to follow them using the links as provided.