ABSTRACT
Ill-nitride-based ultraviolet (UV) light emitters have wide promising applications in solid-state lighting, environmental protection, highly density data recording, nextgeneration photolithography and so on. Recently, deep UV light emitting diode (LED) has become a frontier of nitride semiconductor optical devices for the purpose of developing biosensors and water purifiers [1-3]. To fabricate such devices, AlGaN with high AIN molar fraction is indispensable for carrier confinement and optical transparency. However, it is extremely difficult to grow crack-free AlxGai_xN with high AIN molar fraction on GaN [4]. To overcome this difficulty, our group has utilized AlN/sapphire template to grow high quality crack-free AlxGai_xN (0.2 < x < 0.8) by LPMOVPE [5], confirming that AlN/sapphire template is a good candidate for growth of AlxGai_xN with high AIN molar fraction. Meanwhile, advantages of Ill-nitride SL structures such as AlGaN/GaN SLs and AlGaN/AIN SLs in light emitters have been reported, for instances, strain relief [1,3,6], defect reduction [3], and conductivity improvement [6,7]. Therefore, SL structures with high AIN molar fraction, for example, AlGaN/AIN SLs, should be given enough consideration for fabricating deep UV LEDs. Until now, there are only a few reports on AlGaN/AIN SLs. In this study, we report the structural characterization of AlGaN/AIN SLs with high interface quality grown on AlN/sapphire template by conventional LP-MOVPE.
