Very high carbon incorporation in metalorganic vapor phase epitaxy of heavily doped <i>p</i>-type GaAs

Abstract

Very high C incorporation (≳1020 cm−3) in GaAs was achieved by atmospheric pressure metalorganic vapor phase epitaxy (AP-MOVPE) using CCl4 as a dopant gas. Hole densities up to p=1.2×1020 cm−3 (at least three times higher than previously reported by MOVPE) were obtained at a growth temperature of 600 °C and a V/III ratio of 2.8. The highest atomic C concentration was 1.5×1020 cm−3. The hole mobilities were ∼50% larger than previously reported. CCl4 was found to suppress the formation of gallium droplets and whisker growth which normally occur under low-temperature, low V/III ratio growth conditions, allowing the growth of thin (&amp;lt;1 μm) heavily doped layers with mirror-like surface morphologies. Layers with p∼1×1020 cm−3 showed a lattice contraction with Δa/a=−9.3×10−4. Photoluminescence studies indicate a significant band-gap shrinkage at high doping levels.