Structure and Process of Infrared Hot Electron Transistor Arrays

Richard Fu

doi:10.3390/s120506508

Abstract

An infrared hot-electron transistor (IHET) 5 × 8 array with a common base configuration that allows two-terminal readout integration was investigated and fabricated for the first time. The IHET structure provides a maximum factor of six in improvement in the photocurrent to dark current ratio compared to the basic quantum well infrared photodetector (QWIP), and hence it improved the array S/N ratio by the same factor. The study also showed for the first time that there is no electrical cross-talk among individual detectors, even though they share the same emitter and base contacts. Thus, the IHET structure is compatible with existing electronic readout circuits for photoconductors in producing sensitive focal plane arrays.

Highlights

There is an urgent need for affordable, sensitive and high resolution long wavelength (λ ~ 10 μm) infrared focal plane arrays (LWIR FPAs) for large area persistent surveillance
The objective of this work is to demonstrate an advanced quantum well infrared photodetector (QWIP) sensor in a small exploratory array format, which is capable of suppressing the detector dark current
We propose an architecture that will require only one individual contact for each infrared hot-electron transistor (IHET), and it is more compatible with the existing readout integrated circuits (ROICs)

Summary

Introduction

There is an urgent need for affordable, sensitive and high resolution long wavelength (λ ~ 10 μm) infrared focal plane arrays (LWIR FPAs) for large area persistent surveillance. A LWIR camera with resolution of one million pixels (MP) or more is required [1]. The conventional LWIR FPAs are expensive and the resolution is limited to 0.3 MP. Quantum well infrared photodetector (QWIP) FPAs are less expensive and potentially offer higher resolutions. We recently demonstrated several 1 MP corrugated-QWIP LWIR FPA cameras, which show great promise for this application [2]. To further improve the technology, it is important to increase the detector sensitivity and photocurrent to dark current ratio of the FPAs. In the very long wavelength (VLWIR, λ ~ 14 μm) regime, the dark current

Objectives

Results

Conclusion