Electroluminescence (EL) efficiency, deep electron and hole traps spectra, microcathodoluminescence (MCL), electron beam induced current (EBIC) imaging, and MCL spectra were studied for blue GaN/InGaN multi-quantum-well (MQW) light emitting diodes differing by the temperature at which the GaN barriers of the MQW active region were grown. It was found that increasing the growth temperature from 850 to 920◦C very strongly suppressed the formation of deep electron traps with level at Ec-1 eV in the GaN barriers and of the hole traps with levels at Ev+0.7 eV in InGaN QWs. The suppression of the formation of the Ec-1 eV electron trap, a known prominent nonradiative recombination center in n-GaN, improved the carrier injection efficiency into the InGaN QWs and increased the external quantum efficiency by about 9%. EBIC and MCL imaging showed that the density of threading dislocations and terminating them V-pits was relatively low and similar for both studied growth temperatures, close to 108 cm−2. The cross-sectional dimensions of the V-pits were measurably higher for increased growth temperature. However, the rather low dislocation density and rather high dimensions of the V-pits were believed to result in minor contribution of these defects to the observed EL efficiency changes.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials