15III–V Semiconductors for Infrared Detectors
P. C. Klipstein
SemiConductor Devices, P.O. Box 2250, Haifa, 31021, Israel
15.1 Introduction
In 1970, Leo Esaki and Ray Tsu proposed the semiconductor superlattice [1]. Three years later, together with Sai‐Halasz, they proposed the InAs/GaSb type II superlattice (T2SL), with tunable overlapping superlattice mini‐bands [2]. Their ideas quickly gathered support in many device areas, and a large number of patents and articles appeared over the following years. Nowhere better has their vision been realized, than in the field of infrared detectors. Today, it is possible to manufacture high‐quality T2SL detector arrays, with cut‐off wavelengths selectable anywhere within the long, medium, or short wavelength infrared atmospheric windows (LWIR, MWIR, and SWIR; see Figure 15.1).

Figure 15.1 Typical atmospheric transmission for wavelengths between 1 and 15 μm (taken from https://en.wikipedia.org/wiki/Infrared).
The first III–V semiconductor IR detectors appeared more than 60 years ago with, for example, low‐noise photodiodes fabricated from InSb [3]. InSb was particularly attractive because it could be grown with high quality and a low background impurity concentration, significantly below 1 ppm. In addition, the bandgap wavelength of 5.4 μm at 77 K is almost perfectly matched to the edge of the MWIR atmospheric window. At this temperature, photodiodes ...