Semipolar (11-22) AlN Grown on m-Plane Sapphire by Flow-Rate Modulation Epitaxy for Vacuum-Ultraviolet Photodetection

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 mu m-thick III-FME AIN film are reduced to 346 arcsec and 641 arcsec, respectively. Metal-semiconductor-metal AlN-based photodetectors prepared on the asgrown (11-22) AlN demonstrate the remarkable operating characteristics with a high photo-to-dark-current ratio of 740-2.27 x 10(4) and responsivity of 6-20 mA/W under 185 nm illumination, which implies promising application in vacuum-ultraviolet photodetection field.

Automated summary

Semipolar (11-22) AlN films grown on m-plane sapphire are investigated using flow-rate modulation epitaxy (FME) and show improved film quality and reduced defect density. Photodetectors based on these films demonstrate excellent performance and have promising applications.