Electrical properties of in situ As doped Hg1-xCdxTe epilayers grown by molecular beam epitaxy

The electrical properties of extrinsic in situ doped mercury cadmium tellur ide (Hg1-xCdxTe) epilayers grown by molecular beam epitaxy on (211)B CdTe/S i and CdZnTe substrates are studied. The doping is performed with an elemen tal arsenic source. HgCdTe epilayers with a CdTe mole fraction between 0.23 and 0.36 are grown at substrate temperatures of 175-185 degreesC. The temp erature dependent Hall effect characteristics of the grown samples are meas ured by the van der Pauw technique. A magnetic field of up to 0.8 T is used in these measurements. An analysis of the Hall coefficient in the temperat ure range of 40-300 K with a fitting based on a two-band nonparabolic Kane model. a fully ionized compensating donor concentration, and two independen t discrete acceptor levels is reported. In addition. the fitting results of a three-band modeling of Hall effect results are compared to published dat a on p-type Hg1-xCdxTe Both as-grown and annealed samples are used in this study. All of the as-grown samples showed n-type characteristics whereas an nealed samples showed p-type characteristics. The minority carrier lifetime s of arsenic doped epilayers measured by a photoconductive decay method are presented. In this work, an AlGaAs laser of wavelength 850 nm with a pulse length of 10-90 ns is used. The electron lifetimes obtained from this stud y are compared to published minority electron lifetimes in p-type HgCdTe. T heoretical electron lifetimes of p-type Hg1-xCdxTe material are reported an d a comparison to published electron lifetimes is also given. (C) 2001 Amer ican Vacuum Society.