Experimental energy difference between heavy- or light-hole valence band and crystal-field split-off-hole valence band in AlxGa1−xN

The energy difference between heavy- or light-hole (HH or LH) and crystal-field split-off-hole (CH) valence bands of m- and c-plane AlxGa1−xN was experimentally investigated as the peak-energy difference between (E⊥C)- and (E‖C)-polarized emissions. The energy difference was zero at x≈0.73–0.78. However, this value was significantly larger than x≈0.36–0.41, at which the spontaneous surface-emission intensities of E⊥C and E‖C polarizations from the AlxGa1−xN were equal. These results suggest a shorter carrier lifetime (larger optical gain) in the CH than in the HH and/or LH.