Ammonia: A source of hydrogen dopant for InN layers grown by metal organic vapor phase epitaxy

Thermal annealing of InN layers grown by metal organic vapor phase epitaxy (MOVPE) is investigated in nitrogen atmosphere for temperatures ranging from 400 to $550°C$ and for heat treatment times up to 12 h. This treatment results in hydrogen outdiffusion, lowering significantly the residual $n$-type background doping. This mechanism is shown to be reversible through thermal annealing under ammonia atmosphere, responsible of hydrogen incorporation during growth. These results establish a MOVPE process allowing the obtention of InN samples, which exhibit similar electrical properties than molecular beam epitaxy grown samples: a key issue in view of future industrial production of InN based devices.