Carrier relaxation dynamics and steady-state charge distributions in coupled InGaN/GaN multiple and single quantum wells

S. Khatsevich, D. H. Rich, S. Keller, S. P. Denbaars

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7 Scopus citations

Abstract

We have examined the carrier capture dynamics and excitation dependent charge distributions of coupled InGaNGaN multiple quantum well samples. We measured the temporal evolution of time-delayed cathodoluminescence (CL) spectra to study the temperature- and excitation-dependent transfer of carriers from a surrounding confinement region into a coupled single quantum well. Samples possessing two different structures for the confinement region [i.e., number of quantum wells (QWs) and varying widths] were examined with CL. In order to study state filling of the SQW and QWs in the confinement region, we calculated the quasi-Fermi levels and carrier densities by utilizing a model that involves self-consistent solutions of the nonlinear Poisson-Schrödinger equation for wurtzite QWs including strain, deformation potentials, and polarization fields. Band-edge and effective mass parameters were first obtained from a strain- and In composition-dependent kp calculation for wurtzite Inx Ga1-x N, using a 6×6 kp Hamiltonian in the { 0001 } representation. The model shows that the difference in the quasi-Fermi levels between the confinement and SQW regions decreases with increasing excitation and temperature. Likewise, a reversal in the relative magnitude of the carrier densities between these two regions occurs at a certain temperature and excitation. Furthermore, the results for the model describing the steady-state excitation are consistent with those for the transient excitation in time-resolved CL, which also exhibit a marked increase in the rate of carrier transfer to the SQW region as the temperature increases.

Original languageEnglish
Article number093515
JournalJournal of Applied Physics
Volume101
Issue number9
DOIs
StatePublished - 22 May 2007

ASJC Scopus subject areas

  • Physics and Astronomy (all)

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