Growth and characterizations of A1GaN/GaN heterostructures using multi-A1N buffer layers in plasma-assisted molecular beam epitaxy

摘要

A1GaN/GaN single heterostructures (SH) were grown on sapphire (0001) substrates by plasma-assisted molecular beam epitaxy. It was found that multi-A1N buffer layers are effective to improve the two-dimensional electron gas (2DEG) mobility. High 2DEG mobility of about 1200 cm~2/V s at room temperature was obtained by inserting 4 periods of A1N buffer layers. It is considered that the improvement resulted from the reduction of dislocations in the films by the multi-A1N buffer layers. It was also found that when the periods of the A1N buffer layer were 6, cracks were generated on the surface resulting in a reduction of the mobility.