Nonradiative recombination processes of carriers in InGaN/GaN probed by the microscopic transient lens spectroscopy

Temporally and spatially resolved observations of the nonradiative recombination (NR) processes of carriers in low dislocated GaN and InGaN/GaN were successfully obtained by using microscopic transient lens spectroscopy. The heat generations and conductivities of NR processes were detected by the signal intensities and the time profiles. We found that the thermal conductivities were not so different at the seed region (threading dislocation density (TDD)=1–2×109 cm−2) and the wing region (TDD=1–2×106 cm−2) of air-bridged lateral epitaxially grown GaN and InGaN/GaN, but the amount of heat generated at the wing regions was much smaller than that at the seed regions.