Mechanism of arsenic incorporation and electrical properties in CdTe layers grown by metalorganic vapor phase epitaxy

Abstract

The As doping mechanism in (100) CdTe layers grown on (100) GaAs by atmospheric-pressure metalorganic vapor phase epitaxy was studied. Triethylarsine (TEAs) was used as a dopant source. The source materials used were dimethylcadmium (DMCd) and diethyltelluride (DETe). The As incorporation was enhanced by decreasing the DETe flow rate under a fixed DMCd flow condition, and by lowering the growth temperature. Assuming 100% activation of As, the As incorporation efficiency was estimated to be about 0.1%. The As incorporation was dominated by the sticking rate of the As species onto the Cd species. The hole concentration was controlled from 2×1015 to 3×1016 cm−3 in proportion to the TEAs flow rate below 1×10−7 mol/min. Those doped layers showed hole mobilities as high as 75 cm2/V s. Low-temperature photoluminescence (PL) studies revealed that a neutral-acceptor bound-exciton at 1.5901 eV is due to a substitutional As acceptor on the Te site. The As ionization energy was about 90 meV from the PL and electrical measurements.