The management of stress in MOCVD-grown InGaN/GaN LED multilayer structures on Si(1 1 1) substrates

Abstract

The tensile stress in light-emitting diode (LED)-on-Si(1 1 1) multilayer structures must be reduced so that it does not compromise the multiple quantum well emission wavelength uniformity and structural stability. In this paper it is shown for non-optimized LED structures grown on Si(1 1 1) substrates that both emission wavelength uniformity and structural stability can be achieved within the same growth process. In order to gain a deeper understanding of the stress distribution within such a structure, cross-sectional Raman and photo-luminescence spectroscopy techniques were developed. It is observed that for a Si:GaN layer grown on a low-temperature (LT) AlN intermediate layer there is a decrease in compressive stress with increasing Si:GaN layer thickness during MOCVD growth which leads to a high level of tensile stress in the upper part of the layer. This may lead to the development of cracks during cooling to room temperature. Such a phenomenon may be associated with annihilation of defects such as dislocations. Therefore, a reduction of dislocation intensity should take place at the early stage of GaN growth on an AlN or AlGaN layer in order to reduce a build up of tensile stress with thickness. Furthermore, it is also shown that a prolonged three dimensional GaN island growth on a LT AlN interlayer for the reduction of dislocations may result in a reduction in the compressive stress in the resulting GaN layer.

Epitaxial growth of group III-nitride films by pulsed laser deposition and their use in the development of LED devices

“…To solve these problems, low temperature growth of GaN films by MOCVD and MBE has been conducted [150][151][152][153]. However, the GaN films grown by MOCVD and MBE at low temperature usually show poor quality due to the fact that the low temperature growth fails to supply enough energy for the migration of precursors on the substrates in those cases.…”

Large-area, thermally-sulfurized WS2 thin films: control of growth direction and use as a substrate for GaN epitaxy

“…The limited availability and high cost of bulk gallium nitride (GaN) has led to most GaN layers being deposited on substrates like sapphire [1] or silicon [2] which have a large lattice and thermal mismatch [3]. This results in epilayers with relatively high defect densities [4] which consequently impacts device performance [5,6].…”