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​Indium Arsenide Detectors

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Indium Arsenide Short Form Catalog in PDF Format

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J12 Series detectors are high-quality Indium Arsenide photodiodes for use in the 1 to 3.8 µm wavelength range. The equivalent circuit is a photon-generated current source Iph with parallel capacitance Cd, shunt resistance Rd, and series resistance Rs (Fig. 1). The output signal current Is is defined as:

Is = Iph Rd/Rd + Rs + Rload

Rd varies as a function of detector temperature (Fig. 2). Rs depends on the position of the source light spot on the detector surface; it varies with the distance from the spot to the detector contact ring . When Rs is small compared to Rd it may be disregarded, but with room temperature InAs the effects of Rs are significant.

Figure 1	Figure 2​​

Responsivity

The effect of Rs on the apparent response of an InAs detector is illustrated below. At 22°C, Rs and Rd may have the same order of magnitude (~10 ohms). As a result, although incident photons generate carriers uniformly over the detector area, some of the carriers generated near the center of the area may be "shunted away" through Rd and fail to reach the contact ring. This results in a "dip" in response at the center of the detector's active area (Fig. 3). The effect is less pronounced in small-area detectors, which have higher Rd and less surface area. The effect is also reduced or eliminated by cooling the diode, thereby increasing the detector Rd.

 

Figure 3

Temperature Effects: Cooling an InAs photodiode reduces noise and improves detect​ivity (Fig. 4). Cooling also increases shunt resistance Rd as described in the previous section, allowing more of the photocurrent Iph to reach the contact ring. The result is an increase in the diode response (Fig. 3). For high-power applications such as pulsed laser detection, cooling is generally not necessary. For sensitive, low-power applications such as temperature measurements, the InAs detector should be cooled or at least temperature-stabilized. Stabilizing the temperature near 22°C room temperature will not improve performance, but will prevent changes in detector response due to ambient temperature drift.

Figure 4	Figure 5​

Applications

• Laser Warning Receivers
  
• Process Control Monitors
  
• Temperature Sensors
  
• Pulsed Laser Monitors
  
• Infrared Spectroscopy
  
• Power Meters

Thermoelectric Cooler Operation: Figure 6 shows typical power requirements for the TE1, TE2 and TE3 coolers. The built-in thermistor can be used to monitor or control the temperature. Figure 7 shows typical thermistor resistance vs. temperature values. Sensitivity, cutoff wavelength and response uniformity are all functions of temperature. Detector temperature should be optimized for a particular application.

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Figure 6	Figure 7

CMAMP assembly includes heat sink, temperature controller and transimpedance amplifier for the J12TE packages.

Operating Circuit

The recommended operating circuit for most applications is an operational amplifier in a negative-feedback transimpedance configuration (Fig. 8). The feedback circuit converts the detector output current to a voltage, while the op-amp maintains the detector near zero-volt bias for lowest noise. Because RD varies significantly with temperature, selection of the proper op-amp will depend on the detector operating temperature as well as the desired bandwidth. The feedback resistor RF should be at least 10x greater than RD for best signal-to-noise ratio. Judson has preamplifiers for optimum performance with each detector type. For high frequency applications, the detector may be reverse biased and terminated into a low impedance load (Fig. 9). Maximum reverse bias is 1 volt.

Figure 8	Figure 9​

Advantages of InAs

Unlike the photoconductors commonly used in the 1-3.8 µm wavelength region, InAs operates in the photovoltaic mode and does not require a bias current for operation. This makes InAs the better choice for DC and low-frequency applications, as it does not exhibit the low-frequency or "1/f" noise characteristic of the photoconductors PbS, PbSe, and HgCdTe (Fig. 10). InAs also offers superior pulse response for applications in monitoring and detecting high-speed pulsed lasers.

 

Figure 10

Models

The J12 Series Indium Arsenide (InAs) detectors are photovoltaic infrared photodiodes sensitive in the 1.0 to 3.8 µm wavelength region. Diode sensitivity, speed of response, impedance and peak wavelength can be optimized by operation at the proper temperature. Judson offers a variety of convenient packages for room temperature and thermoelectrically cooled operation. Linear arrays, X-Y position sensors and special configurations are also available.

J12 Series Room Temperature InAs Detectors: These photodiodes operate at ambient temperatures and are excellent for wide bandwidth (DC to 16MHz) applications such as infrared laser monitors and fast temperature sensors. The devices are available in 0.25 mm, 1 mm or 2 mm diameter active sizes and are mounted in the 18C, 5AP or convenient LD2 BNC connector packages. For low frequency applications (DC to 50KHz) the Model PA-5 transimpedance gain preamplifier is strongly recommended. The PA-5 has extremely low voltage noise, low offset voltage and adjustable gain for the best possible match to these low shunt resistance detectors. For high speed applications, the Model PA-101 (5Hz to 1MHz) preamplifier can be used. InAs detectors can be reverse-biased to reduce junction capacitance and improve frequency response.

Thermoelectrically Cooled Indium Arsenide

J12TE1 Series 1-Stage Thermoelectrically Cooled InAs: The J12TE1 Series detectors are high quality temperature stabilized InAs detectors mounted on a one stage thermoelectric cooler. The TE1 series was developed for applications such as temperature monitoring, power meters and infrared spectroscopy where low cost, responsivity, stability and low noise are important issues.

J12TE2 Series 2-Stage Thermoelectrically Cooled InAs: The J12TE2 Series detectors are high quality InAs photodiodes mounted with thermistors on two-stage thermoelectric coolers and hermetically sealed package. The 66D package is standard, with the 66C or 66S packages available as options. At the standard operating temperature of -40°C, the J12TE2 Series detectors have a much higher shunt resistance than room temperature detectors, resulting in higher responsivity, lower noise and better stability for DC or chopped light applications. See Figs. 6 and 7 for thermoelectric cooler operating information.

J12TE3 Series 3-Stage Thermoelectrically Cooled InAs: The J12TE3 Series detectors are high quality InAs photodiodes mounted in the 66D, 66C, or 66S package which includes a built-in thermistor, three stage thermoelectric cooler and hermetically sealed package. J12TE3 devices are ideal for critical military, space or industrial applications requiring high detectivity, good uniformity of response and wide bandwidth.

J12TE4 Series 4-Stage Thermoelectrically Cooled InAs: The J12TE4 Series detectors are high quality InAs photodiodes mounted in the 3CN package which includes a built-in thermistor, four stage thermoelectric cooler and hermetically sealed package.

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Model Number	Part Number	Active Size (dia.) (mm)	Operating Tempera- ture	Cutoff Wave- length (50%) @ lco (µm)	Respon- sivity @ lp (A/W)	Shunt Resistance RD @ VR = 10mV		Maximum NEP @ lpeak and 1KHz (pW/Hz1/2)	Minimum D* @ lpeak and 1KHz (Jones) (cmHz1/2W-1)	Capacitance CD @ VR = 0V (pF)	Optional Packages and Accessories
						Min.	Typ.
						(W)	(W)
J12 Series Room Temperature InAs
J12-18C-R250U	420002	0.25	22°C	3.60	1.5	200	300	6	3.7E9	50	LD2
J12-18C-R01M	420003	1.00			1.0	15	25	33	2.7E9	400
J12-5AP-R02M	420011	2.00			0.8	5	10	71	2.5E9	1600
J12TE1 Series One-Stage Thermoelectrically Cooled InAs
J12TE1-37S-R250U	420088	0.25	-20°C	3.50	1.5	2000	3000	1.8	1.3E10	50	HS1, CM21
J12TE1-37S-R01M	420061	1.00			1.5	200	300	5.6	1.6E10	400
J12TE1-37S-R02M	420065	2.00			1.25	50	90	13	1.3E10	1600
J12TE2 Series Two-Stage Thermoelectrically Cooled InAs
J12TE2-66D-R250U	420083	0.25	-40°C	3.45	1.5	12K	24K	0.69	3.2E10	50	HS Amp, HS1, CM21, CM Amp
J12TE2-66D-R01M	420041	1.00				1.2K	2.4K	2.2	4.1E10	400
J12TE2-66D-R02M	420089	2.00				300	500	4.4	4.1E10	1600
J12TE3 Series Three-Stage Thermoelectrically Cooled InAs
J12TE3-66D-R250U	420081	0.25	-65°C	3.40	1.5	160K	320K	0.18	1.2E11	50	HS Amp, HS1, CM21, CM Amp
J12TE3-66D-R01M	420056	1.00				10K	20K	0.71	1.2E11	400
J12TE3-66D-R1.5M	420063	1.50				5K	10K	1.0	1.3E11	800
J12TE3-66D-R02M	420098	2.00				2.5K	5K	1.4	1.2E11	1600
J12TE4 Series Four-Stage Thermoelectrically Cooled InAs
J12TE4-3CN-R250U		0.25	-85°C	3.30	1.5	400K	800K	0.11	2.1E11	50	HS Amp, HS1, CM21, CM Amp
J12TE4-3CN-R01M	420093	1.00				25K	50K	0.43	2.1E11	400
J12TE4-3CN-R02M-B		2.00				6.5K	13K	0.84	2.1E11	1600​

 

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18C Package	5AP Package

 

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37S Package	66D Package

 

3CN Package