Growth mode modulation and crystalline quality improvement of highly relaxed n-Al0.6Ga0.4N on high-temperature-annealing AlN/sapphire template via SiH4-pretreatment

High-quality AlGaN-based film is the key to attain efficient deep ultraviolet emitters. In this study, we developed a silane-pretreatment method to modulate the growth mode of n-Al0.6Ga0.4N on high-temperature-annealing AlN/sapphire template (HTA-AlN) and improve the crystalline quality. It’s found that pretreating the surface of HTA-AlN template by SiH4 could disturb the pseudo-crystal epitaxy of n-Al0.6Ga0.4N and prompt the 3D growth at the AlGaN/AlN interface. The stress of n-Al0.6Ga0.4N was thus released rapidly by fresh-born dislocations. During the following growth, the growth mode of n-Al0.6Ga0.4N with SiH4-pretreatment transformed quickly from 3D to 2D, and the stress was released gradually because of the dislocation inclination. Besides, the threading dislocation density of 6 µm-thick n-Al0.6Ga0.4N with SiH4-pretreatment was reduced to 8.6 × 108 cm−2, which was one third of that without SiH4-pretreatments. This work paves the way for preparation and improvement of the DUV emitters.