GaN/AlGaN multiple quantum wells grown on transparent and conductive (-201)-oriented β-Ga₂O₃ substrate for UV vertical light emitting devices

GaN/AlGaN multiple quantum wells (MQWs) are grown on a $2¯01$-oriented β-Ga₂O₃ substrate. The optical and structural characteristics of the MQW structure are compared with those of a similar structure grown on sapphire. Scanning transmission electron microscopy and atomic force microscopy images show that the MQW structure exhibits higher crystalline quality of well-defined quantum wells when compared to a similar structure grown on sapphire. X-ray diffraction rocking curve and photoluminescence excitation analyses confirm the lower density of dislocation defects in the sample grown on a β-Ga₂O₃ substrate. A detailed analysis of time-integrated and time-resolved photoluminescence measurements shows that the MQWs grown on a β-Ga₂O₃ substrate are of higher optical quality. Our work indicates that the $2¯01$-oriented β-Ga₂O₃ substrate can be a potential candidate for UV vertical emitting devices.