Mechanisms preventing trench defect formation in InGaN/GaN quantum well structures using hydrogen during GaN barrier growth

14 Aug 2017

Here, we study the mechanisms underlying a method used to limit the formation of trench defects in InGaN/GaN quantum well structures by using H2 in the carrier gas for the growth of GaN barriers. The method leads to a complete removal of the trench defects by preventing the formation of basal-plane stacking faults from which trench defects originate, as well as preventing the formation of stacking mismatch boundaries. The penalty paid for the absence of trench defects is the formation of InGaN wells with gross well-width fluctuations where the H2 gas has etched away the indium locally. Where a fully formed trench defect (stacking mismatch boundary opened as V-shaped ditch) already exists in the structure, the GaN barrier growth method using H2 results in a strongly disturbed structure of the quantum well stack in the enclosed region, with the quantum wells and barriers being in places significantly thinner than their counterparts in the surrounding material.