Analytical and numerical evaluation of electron-injection detector optimized for SWIR photon detection

Abstract

Recent results from our electron-injection detectors as well as other heterojunction phototransistors with gain suggest that these devices are useful in many applications including medical imaging, light detection and ranging, and low-light level imaging. However, there are many parameters to optimize such structures. Earlier, we showed a good agreement between experimental results and our models. In this paper, we provide detailed analytical models for rise time, gain, and dark current that very accurately evaluate key parameters of the device. These show an excellent agreement with detailed three-dimensional numerical simulations. We also explore a figure of merit that is useful for low-light-detection applications. Based on this figure of merit, we examine the ultimate sensitivity of the device. Furthermore, we explore the effects of variations in some of the key parameters in the device design and present an optimum structure for the best figure of merit. Our models suggest ways to improve the existing devices that we have, and may be a guideline for similar phototransistors.

Engineering the gain-bandwidth product of phototransistor diodes

“…This structure has been comprehensively studied with the aid of simulation tools to characterize the effects of several design parameters (such as the thickness, composition, and doping of the epitaxial layers) on the device performance. [23][24][25] The type-B structure is somewhat similar to that of type-A, where the In 0.52 Al 0.48 As electron-blocking layer has been removed, and the doping of the trapping layer reduced to 5 Â 10 17 cm À3 . Finally, type-C structure consists of a heterojunction phototransistor (HPT), entirely based on the InP/InGaAs material system.…”

Recent advances in infrared imagers: toward thermodynamic and quantum limits of photon sensitivity

“…A typical EI geometry and band structure is shown in figure 13: a large area absorption region corresponding to the PT collector is coupled to a small electronic volume consisting of the emitter and floating base, acting as charge injector for amplification [115]. The photogenerated charge is transported laterally to the multiplication region thanks to diffusion and built-in field, as shown in figure 13(b), and subsequently 'compressed' in a small-area trapping layer in the injector [116][117][118]. As a result, the floating base potential barrier is modulated, as shown in figure 13(c), similarly to the VB in the pump-gate jot device, enabling the gain of the device [119].…”