INSB-BASED MATERIALS FOR DETECTORS

The development of new epitaxial techniques has given rise to a variety of novel material combinations. Pseudomorphic combinations where the partners have lattice constants which differ by more than 1 % are currently being extensively studied. The built-in strain can alter the symmetry and magnitudes of the bandgaps concerned. The growth and properties of narrow-gap semiconductor systems are reviewed together with their use as components for strained-layer structures. The materials discussed are InSb, InAs and the alloys of these two compounds. The alloy system InAs(1-x)Sb(x) is prone to metallurgical problems such as ordering and phase separation in the mid-alloy range but high-mobility samples have been grown. Other alloy systems are also affected by similar problems. Spike-doped and n-i-p-i structures are studied in InSb and InAs. Minimal dopant diffusion is found. The control of the material properties achieved has enabled the fabrication of a number of prototype device structures including n-i-p-i photodetectors and resonant interband tunnelling structures with inversion barriers.