P-type as-doping of Hg_1−xCd_xTe grown by MOMBE

Abstract

This paper presents a study of both as-grown and annealed p-type Hg_1−xCd_xTe layers that were doped using a cadmium arsenide source. It is shown that by using a metalorganic molecular beam epitaxy system stable and reproducible p-type HgCdTe:As layers were obtained through direct homogeneous doping. The hole concentrations in the as-grown and annealed samples were 8 × 10¹⁶ to 3 × 10¹⁷ cm⁻³ with mobilities of 120∼300 cm²/V-s. The as-grown HgCdTe:As layers had very good crystalline quality with double crystal x-ray rocking curve line-widths ranging from 27 to 42 arc sec. Experimental data demonstrated a strong correlation of hole concentration and mobility with the surface morphology and crystalline quality as a function of Hg flux. The optimum growth window was defined by a narrow range of Hg flux values that gave a smooth film with fewer voids, and higher hole concentrations and mobilities than were obtained at lower or higher Hg fluxes. This correlation between the growth window defined by the surface morphology and the dopant behavior was very important for the successful growth of p-type As-doped HgCdTe materials.