Stacking faults in plastically relaxed InGaN epilayers

Abstract

Relaxed InGaN layers have recently gained a lot of interest as potential pseudo-substrates for InGaN-based devices. In this work we study PAMBE grown thick In0.2Ga0.8N layers relaxed through the formation of (a+c)-type misfit dislocations. We show that either Ga/N flux ratio (ΦGa/ΦN) below 0.6 or high nitrogen flux (ΦN) equal to 1.4 μm h−1 results in basal stacking fault (BSF) formation. Structural analysis has shown that stacking faults are I1-type in I3 and I4 configurations. We discuss the interactions between (a+c)-type dislocations and BSFs which depend on stacking fault configuration. Probably due to the lack of defect character of BSFs in I3 configuration, dislocations can cross them. Whereas BSFs in I4 configuration stop the dislocations a few nanometers above them, possibly due to the repulsive interactions between the descending dislocation and the Shockley partial dislocations surrounding the BSFs.