Morphological evolution of the InGaN-based quantum well surface due to a reduced density of threading dislocations in the underlying GaN through higher growth pressure
K. Uchida et al., Morphological evolution of the InGaN-based quantum well surface due to a reduced density of threading dislocations in the underlying GaN through higher growth pressure, JPN J A P 1, 39(4A), 2000, pp. 1635-1641
We have examined how fewer threading dislocations (TDs) in an underlying Ga
N epilayer affects the surface morphology of InGaN/InGaN quantum well (QW)
structures grown by low-pressure metalorganic vapor phase epitaxy. When the
GaN growth pressure was raised from 100 Torr to 400 Torr, the density of p
ure edge and mixed character TDs was reduced due to the low-density formati
on and increase in the size of initially grown GaN islands. However, the de
nsity of pure screw TDs simultaneously increased. The QW surface morphology
strongly depended on the densities of mixed or screw TDs in the underlying
GaN epilayer. We found that the pit density in the surface of the QW struc
ture decreased with a lower density of mixed TDs, and that the QW surface m
orphology then exhibited a pattern of large nanoscale islands if the densit
y of screw TDs simultaneously increased, or a pattern of heavily bunched st
eps if it was unchanged.