Characterisation of reactive ion etching induced type conversion in HgCdTe

Abstract

Magnetic field dependent differential Hall effect and resistivity measurements have been used to study the transport properties of Au-doped Hg/sub 0.77/Cd/sub 0.23/Te which had undergone p to n type conversion by reactive ion etching. Analysing the data by quantitative mobility spectrum analysis shows that after two minutes of etching in a CH/sub 4//H/sub 2/ plasma at 0.4 W cm/sup -2/ RF power density, the 17 /spl mu/m thick H/sub 0.77/Cd/sub 0.23/Te epilayer had been totally converted from p- to n-type down to the substrate. This is in stark contrast to results on Hg/sub 0.69/Cd/sub 0.31/Te which indicate a conversion depth of 2-3 /spl mu/m. The analysis indicates the presence of two electron species with peak conductivity at 2.3/spl times/10/sup 5/ cm 2 V/sup -1/ s/sup -1/ and 9.3/spl times/10/sup 4/ cm/sup 2/ V/sup -1/ s/sup -1/ respectively. A depth profile of these two carriers is also presented.