Optimized growth of AlN templates for back-illuminated AlGaN-based solar-blind ultraviolet photodetectors by MOCVD
Abstract
In this paper, the AlN templates with different cycles of mesothermal AlN (MT-AlN) interlayer are prepared by metal-organic chemical vapor deposition (MOCVD) at first. The influence of MT-AlN interlayer on the crystalline quality of AlN template has been carefully investigated. The results show that the MT-AlN interlayer played the role of a strain gradient to release the strain of AlN along the growth direction. The crystalline quality, surface morphology and residual compressive stress of AlN templates can be greatly optimized by introducing one cycle of MT-AlN interlayer during the growth of HT-AlN. And then, a PIN structure back-illuminated AlGaN-based solar-blind ultraviolet photodetector (SUV-PD) is further designed, grown and fabricated based on the optimized AlN template. The SUV-PD exhibits a low dark current density, a bandpass spectral responsivity with a peak value of 0.15 A/W at 271 nm, corresponding to an EQE as high as 68.8%, and a response speed of 6.5 ns. These results strongly reflect the high-quality of AlN template prepared by inserting MT-AlN interlayer based on common growth method.
