DEVELOPMENTS AND TRENDS IN MBE OF II-VI HG-BASED COMPOUNDS

We report new developments in MBE of HgCdTe. We show that the crystallographic orientation of the CdTe substrate has a strong influence on the Hg condensation coefficient. A (111)A face requires about one order of magnitude more mercury than a (1 OVER BAR 1 OVER BAR 1 OVER BAR )B face when the growth occurs at 190 degree C, the (100) face falling in between. We confirm that GaAs is still the candidate for replacing CdTe as a substrate. n-type doping using In as a donor has been investigated. High mobilities and also high donor concentrations have been achieved, which is important for future applications. Investigations show that despite the fact that the (100) orientation requires 4-5 times more mercury than the (1 OVER BAR 1 OVER BAR 1 OVER BAR )B orientation, this orientation seems the most suitable in terms of growth control and electron mobilities. The study on the change in the Hg condensation coefficient between HgTe, HgCdTe and HgZnTe has confirmed that Cd weakens the Hg-Te bond whereas Zn is less harmful.