Characterization of QWIP structures prepared on GaAs-patterned substrates

In this work we investigate the preparation of quantum well infrared photodetectors (QWIP) on planar and patterned GaAs substrates. Mesa ridges with various angles between sidewall and substrate (1 0 0) plane were prepared by wet chemical etching. The QWIP structures were grown at a temperature of 700 °C by use of low-pressure MOVPE. Electrical properties and spectral sensitivity of QWIP structures prepared on tilted sidewalls were measured. Our results showed that mesa ridges confined at the sides by facets tilted at 30° to (1 0 0) were most suitable for the QWIP preparation. Asymmetry in room temperature I–V characteristics and a small photovoltaic effect observed at 77 K was ascribed to asymmetric position of delta doping plane in the quantum well.