Role of hydrogen in improving optical quality of GaNAs alloys

Effects of hydrogen irradiation on optical quality of GaNxAs1−x alloys grown by gas source molecular beam epitaxy are studied by photoluminescence (PL) and PL excitation spectroscopies. A strong blue shift of the alloy band gap towards the value of a reference N-free GaAs samples is revealed. Substantial improvements in the optical quality of the structures induced by hydrogen, due to a reduction of band edge potential fluctuations, is also demonstrated. The effect is tentatively attributed to the preferential trapping of hydrogen atoms at the lattice sites with the highest N compositions, which leads to the neutralization of electronic states contributing to the band tail states as well as to the improvement in strain uniformity.