MBE growth of HgCdTe HOT detector heterostructures

Abstract

ABSTRACT Specially designed mercury cadmium telluride (Hg 1-x Cd x Te) p- -n + heterostructures were grown by molecular beam epitaxy (MBE) on CdTe/Si and CdZnTe (211)B-oriented substrates for infrared photo-detector operation at near room temperature. Growth of this structure requires precise control over the crystal quality, compositional profiles, and donor and acceptor doping levels. The doping levels and density of Shockley-Read-Hall centers in the absorber layer must be low enough to realize the benefits of Auger suppression under non-equilibrium device operation. In order to avoid possible contamination from chemical compounds used in traditional substrate mounting methods, non-contact (In-free) substrate mounting was used to grow the structures. High-energy electron diffraction (RHEED) was implemented to develop a substrate thermocouple temperature ramping curve that maintains a constant epilayer temperature. The structures were characterized by FTIR, x-ray diffraction, and temperature dependant Hall measurements. High operating temperature (HOT) detectors were fabricated on these materials and showed good room-temperature response. Keywords: molecular beam epitaxy (MBE), mercury cadmium telluride, HgCdTe, HOT detectors