Arsenic doping upon the deposition of CdTe layers from dimethylcadmium and diisopropyltellurium

The incorporation and activation of arsenic from tris(dimethylamino)arsine in CdTe layers grown by metalorganic chemical vapor deposition with dimethylcadmium and diisopropyltellurium on GaAs substrates are investigated. Arsenic incorporation into CdTe to depend on the crystallographic orientation of the layers and increases in the order (111)B$\to$(100)$\to$(310). Arsenic concentration in the CdTe layers is proportional to the tris(dimethylamino)arsine flow rate to the power of 1.4 and an increase with decrease of the diisopropyltellurium/dimethylcadmium ratio from 1.4 to 0.5. The as-grown CdTe:As layers had $p$-type conductivity with arsenic and hole concentrations of 10$^{17}$–7$\cdot$10$^{18}$ and 2.7$\cdot$10$^{14}$–4.6$\cdot$10$^{15}$ см$^{-3}$, respectively, but the arsenic activation efficiency not exceeding 0.3%. After annealing in argon flow (250–450$^{\circ}$ C) the highest hole concentration and arsenic activation efficiency were 1$\cdot$10$^{17}$ см$^{-3}$ and $\sim$ 4.5% respectively. The ionization energy of arsenic determined from the temperature dependence of the hole concentration was in the range of 98–124 meV. Low-temperature photoluminescence spectra of the layers showed an emission peak with energy of 1.51 eV, which can be attributed to donor-acceptor recombination, where the acceptor is As$_{\mathrm{Te}}$ with ionization energy about 90 meV.