Temperature-dependent Photoluminescence Spectra of InGaN/GaN Multiple Quantum Wells Blue LED Wafers

A blue light LED epitaxial wafer with InGaN/GaN MQW structure was prepared on an Al2O3 (0001) substrate by MOCVD. The 400 mW semiconductor laser with a center wavelength of 405 nm was used as the excitation light source. The PL-spectrum at different temperatures was measured by the self-built 100-330 K low-temperature PL spectrum measurement device and the 350-610 K high-temperature PL measurement device. The peak energy and the relative intensity of InGaN/GaN MQW main luminescence peak, the phonon concomitant peak and the n-GaN yellow band peak, as well as the temperature dependence of the FWHM in the range of 100-610 K were studied by Gaussian peak differentiating and imitating. The results showed that in the temperature range of 100-330 K, the peak energy of the main luminescence peak and the phonon concomitant peak of the epitaxial wafer, as well as the temperature dependence of the FWHM displayed S and W-shaped changes respectively; the complete heating distribution temperature of the carrier was about 150 K; the transition temperature of local carriers from non-heating to heating distribution was 170-190 K; in the high temperature ranged 350-610 K, the changes in peak energy of InGaN/GaN MQW with temperature variation satisfied the Varshni empirical formula. In the In-doped process of MOCVD epitaxial growth, the PL spectrum could be measured by deliberately cooling the temperature; the amount of In-doped was calculated in real time; and the epitaxial wafer growth was monitored online. The above results can be used for the study of PL luminescence mechanism of epitaxial wafers, development of high-temperature online PL spectrum measurement equipment, real-time monitoring of In-doped and so on. © 2019, Science Press. All right reserved.