Radiative and nonradiative recombination mechanisms in nonpolar and semipolar GaInN/GaN quantum wells

Abstract

Via temperature‐dependent time‐resolved photoluminescence spectroscopy, we investigate the radiative and nonradiative recombination processes in thin (quantum well widths of about 1.5 nm) a‐plane, m‐plane, (11true2‾2) and (20true2‾1) GaInN/GaN fivefold quantum well structures of varying indium content grown on low defect density GaN substrates and GaN templates. At room temperature, we observe surprisingly short radiative lifetimes in the range from 100 ps to 1 ns for these structures, being about one to two orders of magnitude shorter than for similar c‐plane quantum wells. This large difference cannot solely be explained by the larger overlap matrix element in non‐ and semipolar wells. Higher exciton binding energies and lower effective density of states masses may contribute to an enhanced radiative probability. The nonradiative recombination exhibits a thermally activated behavior with activation energies of about 10 meV for (11true2‾2) and around 25 meV for nonpolar quantum wells. These values are lower than the quantum well barrier height and the exciton binding energy, but in a similar range as the localization energies estimated from the radiative recombination.

High-Temperature Polarization-Free III-Nitride Solar Cells with Self-Cooling Effects

“…This also corresponds to the relatively strong PL emission at elevated temperatures for the m -plane device shown in Figure (a). It has been observed and confirmed by previous literature that m -plane InGaN QWs have a large radiative recombination rate compared to c -plane counterparts. − On the other hand, the c -plane device has shown an opposite trend compared to the nonpolar device.…”

“…The analytical expressions of different temperature-dependent τ rad , τ SRH , and τ th are described in previous literature . For simplicity, the aforementioned temperature-dependent lifetimes can be expressed as where Δ E is the barrier height for carriers and C rad , C SRH , and C th are temperature-independent coefficients for radiative recombination, Shockley–Read–Hall recombination, and thermionic emission processes. , Then the effective lifetime τ eff contains all three recombination processes: …”

Reduced nonradiative recombination in semipolar green-emitting III-N quantum wells with strain-reducing AlInN buffer layers

“…30 The temperatureindependent contribution 1=s 0 accounts for possible remaining nonradiative recombination at low temperatures due to tunneling of charge carriers to nonradiative centers. 31 As can be seen from Table II, samples A and B1 show similar activation energies below 30 meV, indicating that the same nonradiative recombination mechanism is dominant in both structures. In contrast, sample C1 without a buffer layer shows a larger activation energy of 46 meV.…”

Low-temperature carrier transport across InGaN multiple quantum wells: Evidence of ballistic hole transport

“…To evaluate the ratio of the number of carriers in the deep n d and shallow n sh QWs, IQE values were estimated from temperature-dependent PL decay times and transient amplitudes measured using direct carrier excitation into the QWs at 390 nm. In the estimation procedure it was considered that at short times after the excitation PL decay at 4 K is determined solely by the radiative recombination, and that the inverse PL transient amplitude is proportional to the radiative recombination time [6,7]. below 100 K were found to be temperature independent with a PL decay time of about 4 ns.…”