Indium doping of <i>n</i>-type HgCdTe layers grown by organometallic vapor phase epitaxy

Abstract

n-type doping of mercury cadmium telluride was achieved using trimethylindium as the dopant source. The layers, grown by the alloy growth technique, were doped to ∼5×1018 cm−3. The donor concentration in these layers was found to exhibit a linear dependence on the dopant partial pressure over the carrier concentration range from 5×1016 to 3×1018 cm−3. Reasonably high electron mobility values were observed in these indium-doped layers. Typically, layers with a Cd fraction x=0.23, doped to 3.5×1016 cm−3, exhibited a mobility value of 7.5×104 cm2/V s at 40 K. High electron mobility values, measured over the entire doping regime, suggest a high electrical activity of indium in these layers. The optically measured band edge in these indium-doped layers was observed to shift to higher energy with increasing doping. The band-edge energy values measured in 1×1017 and 3×1018 cm−3 doped layers correspond to x=0.23 and x=0.3, respectively. This increase can be due to an increase in the Cd fraction, or to a Burstein–Moss shift of the band edge with doping.