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 dislo-cations. 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 mu m-thick n-Al0.6Ga0.4N with SiH4-pretreatment was reduced to 8.6 x 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.

Automated summary

In this study, a silane-pretreatment method was developed to improve the growth mode and crystalline quality of n-Al0.6Ga0.4N on a high-temperature-annealing AlN/sapphire template. The use of SiH4 pretreatment disrupted the pseudo-crystal epitaxy of n-Al0.6Ga0.4N, resulting in 3D growth at the AlGaN/AlN interface. This method also led to a significant reduction in threading dislocations density and paves the way for the preparation and improvement of efficient deep ultraviolet emitters.