Effects of hydrogen on doping of GaInNAs grown by gas-source molecular beam epitaxy

Abstract

In this article, we investigate the effects of hydrogen (H) on doping of GaInNAs grown by gas-source molecular beam epitaxy with a rf plasma nitrogen radical beam source. Incorporating nitrogen (N) into p-Ga0.892In0.108As reduces strain and improves thermal stability. With increasing N concentration, more H, from thermally cracked AsH3, is incorporated alongside N into GaInAs. H has two effects on GaInNAs: acting as an isolated donor and passivating shallow dopants by forming complexes. With increasing N concentration, the free carrier concentration in the as-grown highly Be-doped Ga0.892In0.108NxAs1−x is decreased mainly due to H passivation. Rapid thermal annealing (RTA) increases free carrier concentration due to a reduced H level. The as-grown undoped Ga0.924In0.076N0.030As0.970 sample should be p type without H since N introduces a localized acceptor-like level. Our as-grown undoped sample in n-type 6.9×1015 cm−3 due to charge compensation with H donors. After 700 °C RTA, the film becomes p-type 5.7×1016 cm−3 due to the reduced H donors. For highly Si-doped GaInNAs (∼1×1018 cm−3), H mainly passivates the dopants, so the free carrier concentration is increased after RTA.