Effect of Al-rich surface on Se δ-doped GaAs grown by low-pressure metalorganic chemical vapor deposition

We study Se δ-doped GaAs grown by low-pressure metalorganic chemical vapor deposition using hydrogen selenide as a doping precursor. The results of capacitance-voltage measurements show that the very sharp doping profile can be obtained by Se δ-doping on an Al-rich surface and Se segregation is also reduced by making an Al-rich surface after δ-doping. It is essential to utilize the δ-doping sequence which does not have a post-δ-doping purge step to minimize the Se evaporation.