Analysis of polarization anisotropy along the c axis in the photoluminescence of wurtzite GaN

Abstract

The polarization of photoluminescence (PL) was investigated on (11̄00) GaN grown by metalorganic vapor phase epitaxy. We found that the PL intensity and wavelength have polarization dependence parallel and perpendicular to the c axis. We quantitatively analyzed the dependence and found that, since the crystal field of wurtzite GaN along the c axis is strong enough to fix the |z〉 axis of p functions at the c axis, the difference in symmetry between three valence bands appears as the polarization anisotropy in radiative emission, even in bulk GaN.

Study on optimal growth conditions of a-plane GaN grown on r-plane sapphire by metal-organic chemical vapor deposition

“…Unfortunately, epitaxy toward the [0 0 0 1] orientation leads to undesirable spontaneous and piezoelectric polarization effects, which would result in inclined bands and significantly reduce the carrier recombination rate in quantum wells grown on such polar substrates [4,5]. To eliminate such polarization effects, growth along non-polar orientations has been explored for ð1 01 0Þ m-plane GaN on m-plane SiC and (1 0 0) LiAlO 2 substrates, and ð1 12 0Þ a-plane GaN on ð11 0 2Þ r-plane sapphire [6][7][8].…”

Improved quantum efficiency in nonpolar (112̄0) AlGaN/GaN quantum wells grown on GaN prepared by lateral epitaxial overgrowth

“…However, current nonpolar films have high densities of basal plane stacking faults ͑SFs͒ and threading dislocations ͑TDs͒. 2,3 They are possible sources of the local band gap fluctuation and nonradiative recombination centers, which hinder from obtaining high internal quantum efficiency ( int ) or observing in-plane anisotropy 7,10,11 in the transition spectra from three separate valence bands 12 to the conduction band.…”

Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN∕GaN blue light emitting diodes fabricated on freestanding GaN substrates

“…Accordingly, high int can be expected for nonpolar LEDs 12,13 even when highly strained QWs are contained. In addition, nonpolar LEDs are expected to show in-plane optical anisotropy 6,14 according to the polarization selection rules. The polarized light 6,15 could be desirable for the backlighting of liquid crystal displays.…”