Evidence that arsenic is incorporated as As-4 molecules in the molecular beam epitaxial growth of Hg1-xCdxTe : As

Molecular arsenic, As-4, is commonly used as the source for in situ p-type doping of Hg1-xCdxTe grown by molecular beam epitaxy. As incorporated, the arsenic is strongly self-compensated, requiring annealing for its p-type el ectrical activation. Here, a quasithermodynamic model is used to interpret the dependence of the arsenic concentration, c (As), as measured by seconda ry ion mass spectroscopy, on the incident As-4 and Hg fluxes during growth. The results strongly suggest that the As-4 is absorbed in its molecular fo rm rather than being dissociated on the growth surface, as has previously b een assumed. This clearly is relevant to the self-compensation of the arsen ic in as-grown Hg1-xCdxTe. (C) 1999 American Institute of Physics. [S0003-6 951(99)01314-5].