Formation of Three-Dimensional Islands in the Active Region of InGaN Based Light Emitting Diodes Using a Growth Interruption Approach

Abstract

Here, we develop a technological approach to the formation of three-dimensional island-like structures in the active medium of InGaN/GaN based light emitting diodes with an enhanced efficiency with respect to reference quantum wells emitting at the same wavelengths. The reference structures contain two-dimensional In x Ga1– x N quantum wells with x ≤ 18% immediately overgrown after their formation. The method consists in the application of a growth interruption in N2 or N2–H2 mixed atmospheres at different H2 flows and times after the deposition of In0.18Ga0.82N quantum wells, prior to their overgrowth by a GaN layer. The growth interruptions allow a controlled blue shift of the emission peak position with respect to that of the In0.18Ga0.82N structure. The integrated photoluminescence intensity of the so-formed structures is about 1.5 times higher than that of the reference structures emitting at the same peak wavelengths. Light emitting diode structures subjected to growth interruption exhibit higher external quantum efficiency than the reference structures emitting at the same wavelengths. We demonstrate that the observed phenomenon is related to a better charge carrier confinement within a quantum well due to the transformation of planar InGaN layers into laterally connected flat islands.