Strain engineering in GaN layers grown on silicon by molecular beam epitaxy: The critical role of growth temperature

In this work we study both the structural and electrical qualities of AlGaN/GaN high electron mobility transistor heterostructures grown on silicon(1 1 1) by molecular beam epitaxy. Correlations are established between the quality of the structures and the relaxation rate of the mismatch stress in layers grown using ammonia as a nitrogen source. Comparison with layers grown using a nitrogen plasma source confirms the primordial role of the growth temperature for stress relaxation and dislocation filtering.