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.
ASJC Scopus subject areas
- Physics and Astronomy(all)