Diamond Solar Blind UV Detectors on Si Substrates with Graphite Electrodes

The excellent properties of diamond make it a great application potential in the field of solar blind ultraviolet detection. In this paper, heteroepitaxial diamond films were grown on (111) monocrystalline Si substrates by microwave plasma chemical vapor deposition (MPCVD) and the metal-semiconductor-metal(MSM)structure diamond solar blind UV detectors with planar interdigital graphite electrode prepared by pyrolytic photoresist method were produced. The results show that the heteroepitaxial diamond film on silicon substrate is the highly oriented polycrystalline film. The X-ray diffraction peak of the(111)diamond is 43.9°, and the full width at half maximum (FWHM)is 0.093°, while the Raman scattering peak of diamond is 1 332 cm-1 and the FWHM is 4 cm-1, indicating high crystal quality of the heteroepitaxial polycrystalline diamond film. The graphite electrodes were characterized by the optical microscopy and Raman spectroscopy. It shows that compared with the laser ablation method, the pyrolytic photoresist method simplifies the processes and reduces the cost. It is an effective method for preparing graphite electrodes on diamond films. The dark current of the detector with the graphite electrode reaches 2.07×10-8 A at 5 V bias, and the light-to-dark current ratio reaches 77 at 5 V bias. The diamond detector with the graphite electrode has excellent time response performance. The rising time is 30 ms and the falling time is 430 ms. Therefore, the diamond solar blind UV detector with the graphite electrode prepared by pyrolytic photoresist has high performance. © 2024 Editorial Office of Chinese Optics. All rights reserved.