Voltage-tuning in multi-color quantum well infrared photodetector stacks

Abstract

A voltagetunable multicolor triplecoupled InGaAs/GaAs/AlGaAs quantumwell infrared photodetector for 8-12 μm detection Appl.A systematic study of stacked quantum well infrared photodetectors is undertaken to improve the understanding of the voltage-tunable multi-color spectral response. The multi-color capability is achieved by sequentially growing conventional one color detectors, separated by conducting layers. The behavior of the stacked devices is proven to correspond to the individual detectors simply acting in series with each other. The dc resistance, photocurrent and dynamic resistance characteristics of the individual detectors are examined and correlated with the voltage-tuning in the stack.

Multi-band and broad-band infrared detectors based on III–V materials for spectral imaging instruments

“…6 shows a schematic band diagram of the ''stack design,'' which consists of two stacks of MQW structures designed to respond at two different wavelengths within the required broad wavelength band. A similar design scheme was used in the past for tunable multi-band QWIPs [13,14]. If the two MQW structures have dissimilar impedances, a disproportional bias voltage drop across the structures could lead to a dominant photocurrent response from a single structure.…”

“…If the two MQW structures have dissimilar impedances, a disproportional bias voltage drop across the structures could lead to a dominant photocurrent response from a single structure. As the bias voltage changes, response could switch to the other structure, effectively acting as a voltage tunable detector [13,14]. Therefore, in order to keep the broad-band spectral shape unchanged, it is essential to design two MQW structures with similar impedances, at least within the desired operating temperatures and bias voltages.…”

Designs of broadband quantum-well infrared photodetectors and 8–12μm test device results

“…For the 10-lm QWIP, we have L w = 53 nm and x = 0.22 (V b = 0.1914 eV and E 1 = 0.0643 eV). If we use the same doping for the 10-lm QWIP here, we would have very different resistances between the two stacks and the resulting device would have a voltage tunable spectrum [7,8]. Here to balance the two resistances, we increase the doping in the 10-lm QWIP so that the two QWs have the same activation energy.…”

“…Such an approach has been investigated for voltage tunable multicolor QWIPs [7,8]. The advantage of this design is that the responsivity should be the same as the standard QWIP.…”

Optically addressed near and long-wave infrared multiband photodetectors

“…Theory of voltage-tuning in multi-color QWIP stacks has been discussed in the literature. 19,20 However, none of the demonstrated technologies were able to switch bands with externally applied light in the infrared.…”