Growth of Zn δ-doped AlxGa1−xAs (x = 0–0.65) by low pressure metal organic vapour phase epitaxy

We report the experimental results on the growth of Zn δ-doped AlxGa1−xAs by low pressure metal organic vapour phase epitaxy using dimethylzinc as a doping precursor. Zn evaporation from a non-growing AlxGa1−xAs surface during a post δ-doping purge step is very significant in the range of experimental temperatures. In order to minimise the Zn evaporation, a new δ-doping sequence is proposed. Using this new δ-doping sequence, Zn δ-doped GaAs with the highest hole concentration (1.1 × 1020 cm−3) reported to date with a full width at half maximum of 7 nm was obtained, and the effect of the Al content and temperature on the Zn δ-doping concentration of AlxGa1−xAs was investigated. It is revealed that the Zn desorption occurring during a δ-doping step determines the Zn δ-doping concentration and the Zn desorption activation energy decreases with increasing Al content.