Chapter 5 - Homo- and Heterojunction Interfacial Workfunction Internal Photo-Emission Detectors from UV to IR

Abstract

Publisher Summary Infrared (IR) radiation was discovered accidently by Sir Frederick WilliamHerschel (1738–1822. The Second World War dramatically increased the interest in IR detection in which photon detectors were developed to improve the performance. Now the infrared detectors are used in various sectors not only in defense and security, but also in manufacturing, medicine, environment, and various other testing/monitoring applications. This chapter focuses on detection using internal photoemission across an interfacial workfunction in a semiconductor homo- or heterojunction architecture. Although quantum well structures also have a junction and an interface, the energy difference between the two states associated with the transitions are because of the quantization effects in the well material but not at an interface. The detector concepts discussed in the chapter can be applied to any semiconductor material where an interface can be formed. Varying the interfacial workfunction leads to different energy photons to be detected giving rise to different threshold wavelength (λ t ) detectors. The chapter also discusses the way multiband detection is achieved in a single detector element. It also discusses the concept of controlling the operating temperature and responsivity by adjusting the interfacial workfunction in connection with the spin-orbit split-off detectors.