Interband transitions of AlN/Al x Ga1-x N (0.65 aparts per thousandcurrency sign x aparts per thousandcurrency sign 0.85) single quantum wells

Interband transitions of AlN/Al (x) Ga1-x N (0.65 a parts per thousand currency sign x a parts per thousand currency sign 0.85) single quantum wells (SQWs) have been investigated by using photoluminescence (PL) measurements. For SQWs with a well thickness of 1.5 nm, in addition to the dominant PL emission lines (E1), second PL emission lines (E2) with higher energies than E1 are found for x = 0.65, 0.7, and 0.75 at 10 K. The energy differences between E1 and E2 are about 300 similar to 450 meV, and the E2 lines disappear for x a parts per thousand yen 0.8. These results suggest that both the E1 and the E2 lines are attributable to localized exciton recombination in the AlGaN QW region; moreover the E1 and the E2 lines are due to transitions from the first electron subband to the first heavy-hole subband (e1-hh1) and from the second electron subband to the second heavy-hole subband (e2-hh2), respectively.