Lasing mechanism of InGaN-GaN-AlGaN MQW laser diode grown on SiC bylow-pressure metal-organic vapor phase epitaxy

摘要

We studied the lasing mechanism of an InGaN-GaN-AlGaNnmultiquantum-well (MQW) laser diode by making various opticalncharacterizations on the diode. Excitation power dependence ofnphotoluminescence (PL) intensity was obtained to investigate the carriernrecombination process of the laser. Surface emission and edge emissionnwere compared by optical pumping to clarify where the lasing lines werenlocated in relation to the absorption continuum. From the results, wendemonstrate that lasing phenomena in our laser are dominated by freencarriers. PL mapping was also taken on the same laser chip to examinenthe in-cavity bandgap inhomogeneity. We found a very large bandgapnscattering of 100 meV. We also found that the wavelength distributionnhas a periodic modulation. We clarified that the various stimulatednemission lines observed in our lasers are caused by the in-cavitynspatial bandgap inhomogeneity of the InGaN MQW