Improvement of InGaP/GaAs heterointerface quality by controlling AsH3 flow conditions

Heterointerfaces between disordered InGaP on GaAs, whose conduction band offset, ΔEc, is 0.2 eV, can be improved and have less interface charges by controlling the AsH3 cover time and flow rate at the growth interval from GaAs to InGaP by metalorganic chemical vapor deposition. A small AsH3 cover of 5 cc (0.05 min with 100 cc/min) creates a low interface charge density, σ, of 6.4×1010 cm−2. Extending the AsH3 cover to only 25 cc increases σ by one order, even though AsH3 is purged by PH3 for a rather long time after being covered. Interface charges are confirmed to be donors whose energy level is near the conduction band edge. These results show that excess As on the GaAs surface enhances the formation of donor-like defects in the InGaP layer. An As-poor GaAs surface is essential in order to achieve high-quality InGaP/GaAs heterointerfaces.