A schematic diagram of (a) sample structure and (b) conduction energy band in the MQW region.
HRTEM images of (a) sample A, (b) sample B, and (c) sample C with a scale bar of 20 nm.
RT PL spectra (black curves) and PLE spectra (red curves) of samples A, B, and C. The green and blue curves are two fitting curves corresponding to the sigmoidal MQW-related absorption bands of S1 and S2, respectively.
Normalized integrated PL intensity of two emission peaks for (a) sample A, (b) sample B, and (c) sample C, together with the best Arrhenius fitting curves. The insets show the TDPL spectra over the temperature range from 10 K to 300 K. (d) The MQW IQE of three samples as a function of PL peak photon energy.
TRPL decay curves of high-In-content MQWs for (a) sample A, (b) sample B, and (c) sample C, measured at the PL peak photon energy over the temperature range from 10 K to 300 K. The insets in (a) and (b) show the enlarged temporal profiles of samples A and B at 10 K, respectively. (d) Ten Kelvin TRPL decay curves of low-In-content MQWs for three samples measured at the peak photon energy.
PL lifetime τPL, radiative lifetime in the localized states τrad, and nonradiative lifetime in the free/extended states τnr of high-In-content MQWs for (a) sample A, (b) sample B, and (c) sample C across the temperature range derived from Eq. (5).
PL spectra and photon energy dependence of carrier lifetime τPL at 10 K for the high-In-content MQWs of (a) sample A, (b) sample B, and (c) sample C. The blue line is a fitting curve.
Obtained fitting parameters: effective energy gap for the InGaN layer (E eff), PL peak energy (E PL), FWHM of the PL peak, and Stokes shift (Δ Ss). The unit is eV for E eff and E PL, and meV for FWHM and Δ Ss.
Obtained fitting parameters: carrier decay time in the low-In-content MQWs (τ1 and τ2), carriers transfer time from low-In-content region to high-In-content reign (τrise) and carrier decay time in the high-In-content MQWs (τdecay).
Obtained fitting parameters: effective radiative lifetime (τeff,rad), energy similar to mobility edge (E me), and the depth of carrier localization in the high-In-content MQWs (E 0).
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