Fig. 3

Characterization of the AlN-based VUV PD array. Cross section a low-magnification TEM image and b high-resolution TEM image and diffraction images of the AlN/SiC heterojunction. c Raman spectrum of AlN/SiC wafer excited by a 266 nm laser. d Rocking XRD curve of the (0002) crystal face of the AlN film. The small peak to the left of the main peak is the (0004) diffraction peak of SiC. Due to the similar diffraction peak angles of AlN and SiC, the SiC diffraction peak cannot be filtered out completely. e PL spectrum of the AlN film. f Transmittance of the photoresist used for the fabrication of the PD array in the range of 140 ~ 500 nm. The insert shows the transmittance in the VUV range (140 ~ 200 nm). g AFM image of the Pt electrode. The Pt electrode has a thickness of about 6 nm