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

Abstract

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 degrees 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

Origin of background electron concentration in InxGa1−xN alloys

“…cannot be diffused out and is thus responsible for residual n in annealed materials. This reduction of background n by half has been observed in InN grown under different growth conditions by several groups [19,20,32] and validates our discussion above. The reduction factor depends upon the ratio of H to V N concentrations.…”

“…Impurities such as H [14][15][16][17][18][19][20] and O [16,20], nitrogen vacancies (V N ) associated with dislocations [21,22], and In vacancy/N anti-site (V In -N In ) complexes [23] , it is difficult to observe dependence on the growth or post-growth processing parameters and thus difficult to understand the cause of high n in InGaN. We report here a systematic study of the behavior of the background electron concentration in InGaN alloys synthesized by MOCVD in the whole composition range and attempt to pinpoint a possible origin of high n.…”

Morphology and arrangement of InN nanocolumns deposited by radio-frequency sputtering: Effect of the buffer layer

“…High-quality InN has been grown mainly by molecular beam epitaxy (MBE) [3][4][5][6] and metalorganic vapor phase epitaxy (MOVPE) [7][8][9]. The optimal substrate temperature (T s ) for InN growth is close to the decomposition temperature of the material, around 500°C [10].…”

Influence of buffer layers on the microstructure of MOVPE grown a-plane InN

“…[14], from which the background carrier concentration is evaluated to be 1.5 Â 10 18 cm À 3 . We have also attempted thermal annealing of the epilayer in a nitrogen ambient which has been shown to significantly reduce the background concentration due to hydrogen outdiffusion [15]. While we do see a slight red shift (10 meV) in the PL peak position on annealing in nitrogen, we do not see any dramatic improvement in the electrical properties of the epilayer.…”