SWIR diodes of HgCdTe on GaAs substrates grown by metal organic vapor phase epitaxy

Abstract

We report the growth of short wave infrared (SWIR) HgCdTe on (001) GaAs by metal organic vapor phase epitaxy (MOVPE). KOH dissolved in water used as final substrate rinse produce a mirror - like surface and with a hillock density of less than 10cm⁻². It is shown that K element diffuses during layer growth and heat treatment for metal vacancy filling from the GaAs substrate/buffer interface into the MCT with a surface concentration of around low 10¹⁵cm⁻³. The transport properties of undoped MCT layers are dominated by residual K element in the layer. Short wave infrared (SWIR) photovoltaic devices have been fabricated from n on p HgCdTe films on GaAs substrates. The MOVPE grown films were processed into mesa type discrete devices with wet chemical etching employed for mesa delineation and ZnS surface passivation. The photodiode forward and reverse current-voltage characteristics, as well as the temperature dependence of the zero-bias dynamic resistance, were measured in the temperature range of 200-300 K. The zero bais dynamic resistance-area product at 200K and 300K were 5×10⁵ and 3.0×10² ohm-cm², respectively. The relative spectral response cut off wavelength of device at 300K was 2.5μm.