Optical properties of AlGaN quantum well structures

We demonstrate 230-250 nm efficient ultraviolet (UV) photoluminescence (PL) from AlN(AlGaN)/AlGaN multi-quantum-wells (MQWs) fabricated by metalorgani c vapor-phase-epitaxy (MOVPE). Firstly, we show the PL properties of high A l content AlGaN bulk (Al content: 85-95%) emitting from near band-edge. We systematically investigated the PL properties of AlGaN-MQWs consisting of w ide bandgap AlGaN (Al content: 53-100%) barrier. We obtained efficient PL e mission of 234 and 245 nm from AlN/A(0.18)Ga(0.82)N and Al0.8Ga0.2N/Al0.18G a0.82N MQWs, respectively, at 77 K. The optimum value of well thickness was approximately 1.5 nm. The emission from the AlGaN MQWs were several tens o f times stronger than that of bulk AlGaN. We found that the most efficient PL is obtained at around 240 nm from AlCaN MQWs with Al0.8Ga0.2N barriers. Also, we found that the PL from AlGaN MQW is as efficient as that of InGaN QWs at 77 K.