The effects of nitridation on properties of GaN grown on sapphire substrate by metal-organic chemical vapour deposition

Abstract

The material qualities of GaN overlayers grown on (0001) sapphire substrates by metal-organic chemical vapour deposition were investigated as a function of nitridation time. The nitridation of sapphire surface notably affects on the properties of the GaN overlayers, such as surface morphology and structural, optical and electrical properties. The GaN overlayer with a short nitridation time of 30 s shows a good surface morphology, a relatively low background Hall carrier concentration and a high electron mobility, but the defect-related emission around 550 nm increased. Furthermore, for the GaN overlayer with nitridation for 180 s, even though it has a low (102) full width at half-maximum of the high-resolution x-ray diffraction rocking curve, other material properties were degraded owing to the long nitridation time. It was found that material properties have a trade-off relationship with the variation of nitridation time.

Metal organic vapour phase epitaxy of GaN and lateral overgrowth

“…The so-called nitridation step is widely documented and will not be exhaustively discussed. Basically, nitridation is carried out at 1050˚C under NH 3 [34][35][36]. By HRTEM, it is evident that several AlN monolayers are formed on top of the sapphire.…”

Влияние степени нитридизации сапфира и обогащения алюминием зародышевого слоя на структурные свойства слоев AlN

“…Aвторы [7] вообще не обнаружили насыщения процесса нитридизации при экспозиции подложки сапфира, нагретой до 700 • С, в потоке ионов азота [7]. Поскольку скорость прохождения этапов нитридизации зависит от условий ее проведения, кристаллическое качество последующих А III -нитридных слоев зависит от условий нитридизации подложки: температуры, давления аммиака и времени экспозиции в аммиаке [4,9,[13][14][15][16][17].…”

Thermal Properties of GaN Films Grown on Si Substrates

“…The first stage of growth conditions determines the characteristics of the subsequent GaN epitaxial layers. In particular, the nitridation of the substrate surface notably affects the properties of the GaN overlayers, such as surface morphology, and structural and optical properties [1][2][3]. Thus, the study of the initial substrate nitridation can have significant impact.…”