Third-generation infrared photodetector arrays

TLDR

Third‑generation infrared imaging systems are being developed to offer larger pixel counts, higher frame rates, improved thermal resolution, multicolor capability, and on‑chip signal processing, building on first‑ and second‑generation linear and two‑dimensional arrays while confronting complex device structures and fabrication challenges. This paper examines the fundamental and technological issues, including current challenges, involved in developing and deploying third‑generation infrared photon detectors. The authors review HgCdTe photodiodes and quantum‑well photoconductors, and discuss recent focal‑plane arrays based on type‑II strained‑layer superlattices and quantum‑dot photodetectors, highlighting ongoing efforts to overcome fabrication and material growth obstacles.

Abstract

Hitherto, two distinct families of multielement detector arrays have been used for infrared (IR) imaging system applications: linear arrays for scanning systems (first generation) and two-dimensional arrays for staring systems (second generation). Nowadays, third-generation IR systems are being developed which, in the common understanding, provide enhanced capabilities such as larger numbers of pixels, higher frame rates, better thermal resolution, multicolor functionality, and/or other on-chip signal-processing functions. In this paper, fundamental and technological issues associated with the development and exploitation of third-generation IR photon detectors are discussed. In this class of detectors the two main competitors, HgCdTe photodiodes and quantum-well photoconductors, are considered. This is followed by discussions focused on the most recently developed focal plane arrays based on type-II strained-layer superlattices and quantum dot IR photodetectors. The main challenges facing multicolor devices are concerned with complicated device structures, thicker and multilayer material growth, and more difficult device fabrication, especially for large array sizes and/or small pixel dimensions. This paper also presents and discusses the ongoing detector technology challenges that are being addressed in order to develop third-generation infrared photodetector arrays.