Hot carrier relaxation process in InGaN epilayers

Abstract

InGaN epilayers with gallium fractions ranging between 0 and 0.48 have been studied by time-resolved photoluminescence. Layers containing low gallium fractions are associated with low PL emission intensity. For In 0.83 Ga 0.17 N layer, the luminescence decay is 100 times faster in the high energy part of the photoluminescence spectrum than on the low energy part, reflecting the hot carrier recombination process. This is confirmed by the significant blue shift of the photoluminescence spectra for short decay times compared to the time integrated spectrum. It takes about 10 ps for the carriers to reach an equilibrium temperature of 100 K.

Review of the mechanisms for the phonon bottleneck effect in III–V semiconductors and their application for efficient hot carrier solar cells

“…Therefore, a study on the carrier relaxation in high indium composition (i.e., from 0.51 to 1.0) InGaN alloys was systematically implemented by Lagarde et al by comparing the carrier temperature temporal evolution extracted from TRPL. 63 Fast and slow components of carrier cooling were observed. These were attributed to the hot carrier cooling and band edge carrier recombination, which is highly consistent with that found in bulk InN.…”

“…Due to their short carrier relaxation times, InGaN alloys with relatively low indium composition do not appear to be suitable candidates for HCA. Therefore, a study on the carrier relaxation in high indium composition (i.e., from 0.51 to 1.0) InGaN alloys was systematically implemented by Lagarde et al by comparing the carrier temperature temporal evolution extracted from TRPL 63 . Fast and slow components of carrier cooling were observed.…”

Investigation on the effect of indium composition on ultrafast carrier dynamics in InGaN alloys

“…Much work has been done to explore this issue in terms of carrier density, strain relaxation, operation temperature and carrier-defect scattering. [6][7][8][9] However, the indium composition effect on ultrafast carrier dynamics in InGaN alloys at room temperature is still not well investigated heretofore. Because the indium-rich clusters attributing to partial phase segregation are widely observed in InGaN alloys.…”

“…A redshift of PL peak with time delay for each alloy were observed, reflecting the hot carrier relaxation dynamics and a reduction of the band filling effect as the photoexcited carriers recombine. 6) Such a band filling effect is attributed to the phonon bottleneck effect, which could reduce the energy loss rate of hot carriers at high photoexcited carrier density. 18,[27][28][29][30][31] All PL spectra at specific time delays extracting from TRPL could be modeled by a generalized Planck radiation law given by Eq.…”

“…9) Even though the τ effect of these alloys are relatively short, the time that "hot" carriers take to reach room temperature are all longer than 50 ps at least and much longer than those of the In x Ga (1−x) N(i.e., 0 ⩽ x ⩽ 1) alloys in other work. 6,8,31,[35][36][37] It has been know that the hot phonon bottleneck effect could significantly extend the carrier lifetime and be widely observed in low dimensional structure materials. 38) However, it is quite difficult to observe such an effect for further analysis in bulk InGaN alloys.…”