InGaAs - Indium Gallium Arsenide

       InGaAs, or Indium Gallium Arsenide, is a semiconductor which is made up of the elements Indium, Gallium, and Arsenic. Due to its superior electron velocity as compared to the other semiconductors like silicon and gallium arsenide, it is often used in high-power and high-frequency applications. In fiber optics communications, InGaAs is preferred as it serves as a good detector material in bandgap at 1300 and 1550 nanometers. A nanometer is equivalent to 1x10 raised to -9. InGaAs' alternative name is Gallium Indium Arsenide or GaInAs. InGaAs is also used in infrared detectors. It is preferred over germanium as a detector material mainly because of the lower internal generated current or dark current. In short-wave infrared cameras, InGaAs is used as a detector material. Another characteristic of it is its lower multiplication noise than germanium. Its characteristic is important when used as the active multiplication layer of an avalanche photodiode.

InGaAs finds application as a laser medium. Because of its characteristics, it can be employed in devices designed to operate at wavelengths of 905 nm, 980 nm, 1060 nm, and 1300 nm. In researches with lasers, InGaAs quantum dots on GaAs are also under consideration.

InGaAs array

Multiplexed InGaAs linear arrays are available through Judson Technologies. For high performance InGaAs linear arrays, they have the J22M Series which are designed for telecommunication applications operating in the S, C and L band or frequencies. For applications in spectroscopy and thermal imaging, the J23M Series, which are InGaAs linear arrays with extended NIR cutoffs at 1.9 micrometer, 2.2 micrometer, 2.4 micrometer and 2.6 micrometer, is available.

The J22M and J23M arrays are paralleled to buffered complimentary metal oxide semiconductors or CMOS multiplexers. They are available in various sizes such as the 128 and 256 elements with 50 micrometer channel separation and 500 micrometer of picture element height. To minimize internal generated current or dark current and low frequency noise, the integrating amplifier keeps a zero voltage across each InGaAs photodiode. Our MUX design has a characteristic of low noise and wide dynamic range using high input impedance CMOS, charge coupled transimpedance amplifier and four capacitors which may be configured via computer.

InGaAs detector

Indium Gallium Arsenide (InGaAs) detectors and avalanche photodiodes or otherwise popularly known as APD from GPD Optoelectronics Corporation are available though Pro-Lite. This detectors functions from 800 to 1700 nm and are identical to germanium (abbreviated as Ge), but with a characteristic of high sensitivities at low light levels. The availability of InGaAs includes custom packages, submounted, custom filters and windows, large area InGaAs which is up to 5mm, extended range InGaAs which is up to 2.2 micrometer and high speed InGaAs which is up to 4GHz.

Aside from Pro-Lite, InGaAs avalanche photodiodes are also produced by GPD, with areas of active operation at 80 and 200 micrometer. Avalanche photodiodes (APD) may be likened to the photomultiplier tube (PMT) detector. APD exhibits high internal current gain when subjected to reverse-biased voltage in a circuit. This is the characteristic of APD which makes it a better option than regular InGaAs detector because the former is more significantly sensitive to low light levels than the latter. APDs may be available as chip or submount combinations, in TO-46 cases with flat windows, or ball lenses and fiber pigtail packages.

InGaAs photodiode

InGaAs photodiodes reacts to wavelengths of large range. This type of photodiodes finds application as linear arrays, image sensors, and photodiode/amplifier devices and many other circuits. The aforementioned range of InGaAs PIN photodiodes has wider and extended response to spectra or wavelength. Currently, there are three types out in the market, namely: 0.9 micrometer to 1.9 micrometer; 1.0 micrometer to 2.1 micrometer; and 1.2 micrometer to 2.6 micrometer. For applications of dark current reduction, consumers have an available option between single and two-stage thermoelectrically cooled versions. For applications like near infrared (NIR) spectroscopy, chemical process monitoring, gas detection, food quality measurements, and non-destructive testing, long wavelength InGaAs detectors are best suited for.

InGaAs PIN

       Due to the InGaAs PIN photodiodes' characteristics such as small terminal capacitance, low dark current, low noise, and high-speed response, they are suited as near infrared (NIR) detectors. In order for these characteristics to manifest, InGaAs PIN photodiodes must be cooled with thermoelectric cooler. Some pplications of InGaAs PIN are near infrared spectroscopy, optical communications. Furthermore, these applications may be classified into four types: Standard type InGaAs PIN photodiodes – have spectral response range of 0.9 micrometer to 1.7 micrometer. These photodiodes provide high-speed response and low noise due to its feature of low terminal capacitance and a large shunt resistance.

1. Long wavelength InGaAs PIN photodiodes – have spectral response range up to 2.6 micrometer.
2. Image sensors and arrays for spectrophotometry and DWDM channel monitoring – have spectral response range from 0.9 micrometer to 1.67 micrometer and 0.9 micrometer to 2.55 micrometer. These are capable of combination of a one or two-stage thermoelectric cooler.
3. Infrared detector modules – they are made up of InGaAs PIN photodiode, packed with a matched preamplifier and may be connected to a low-voltage direct current source to function.

Hamamatsu Photonics is engaged in the manufacturing of various light emitter or receiver devices whether the application calls for long or short wavelengths. Short wavelengths are around 850 nanometer and long wavelengths are around 1310 nm to 1550 nm. The major applications of such are high speed local area networks or LAN, broadcasting or communications up to 10 Gbps. They manufacture diodes having high sensitivity (0.95 A/W). They also manufacture high performance products for Optical Communications which have state-of-the-art functions like linear image sensors with CMOS ICs, Photo ICs having an Si PIN photodiode coupled with high-speed signal processor on one chip which is often employed in industrial and office automation, or home networks. Hammamatsu also specializes in the manufacture of optoelectronic devices, which can couple a lens or flat window in the packaging.