Effect of gallium nitride template layer strain on the growth of InxGa1-xN∕GaN multiple quantum well light emitting diodes

GaN template layer strain effects on the growth of InGaN∕GaN light emitting diodes devices were investigated. Seven-period InGaN∕GaN multiple quantum well structures (MQW) were deposited on 5 and 15μm GaN template layers. It was found that the electroluminescence emission of the 15μm device was redshifted by approximately 132meV. Triple-axis x-ray diffraction and cross-sectional transmission electron microscopy show that the 15μm template layer device was virtually unstrained while the 5μm layer experienced tensile strain. Dynamic secondary ion mass spectrometry depth profiles show that the 15μm template layer device had an average indium concentration of 11% higher than that of the 5μm template layer device even though the MQW structures were deposited during the same growth run. It was also found that the 15μm layer device had a higher average growth rate than the 5μm template layer device. This difference in indium concentration and growth rate was due to changes in thermodynamic limitations caused by strain differences in the template layers.