Semipolar (11–22) AlN Grown on m-Plane Sapphire by Flow-Rate Modulation Epitaxy for Vacuum-Ultraviolet Photodetection
Jiankun Yang, Yaqi Gao, Wei Zheng, Rui He, Ziqiang Huo, Xiaoli Ji, Junxue Ran, Ruifei Duan, Junxi Wang, Jinmin Li, Tongbo Wei
Abstract
Semipolar (11–22) AlN films grown on m-plane sapphire are investigated by flow-rate modulation epitaxy (FME). The full width of half maximums (FWHMs) of thin AlN film for X-ray rocking curves (XRCs) are reduced from 1398 arcsec for traditional growth to 865 arcsec for III-FME. The reduced defect density is attributed to prolonged Al mobility, which results in the transition of growth mode from quasi three-dimensional to two-dimensional step flow. On-axis FWHM[11–23] and off-axis FWHM[0002] of XRCs for 6 μm-thick III-FME AlN film are reduced to 346 arcsec and 641 arcsec, respectively. Metal–semiconductor–metal AlN-based photodetectors prepared on the as-grown (11–22) AlN demonstrate the remarkable operating characteristics with a high photo-to-dark-current ratio of 740–2.27 × 104 and responsivity of 6–20 mA/W under 185 nm illumination, which implies promising application in vacuum-ultraviolet photodetection field.