Processing of silicon UV-photodetectors

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2001-03, Vol.460 (1), p.165-184
• Main Authors: Thungström, G., Dubaric, E., Svensson, B.G.
• Format: Article
• Language: English
• Subjects: Antireflective coating; Detector processing; Electrical engineering, electronics and photonics; Elektroteknik, elektronik och fotonik; Photodiodes; Silicon photodetector; TECHNOLOGY; TEKNIKVETENSKAP; ultra violet detectors processing; Ultraviolet detector
• ISSN: 0168-9002; 1872-9576; 1872-9576
• DOI: 10.1016/S0168-9002(00)01111-6

UV-enhanced photodetectors of both n +–p and p +–n type have been processed in silicon. Photodetectors of the p +–n type display a responsivity close to the theoretical limit with an antireflective coating of either thermally grown dry silicon dioxide or deposited oxide (TEOS), followed by a short wet oxidising step. This holds, irrespective of whether the detector window is doped by boron through ion implantation or diffusion from a solid source. However, for p +–n photodiodes with a TEOS-oxide in the as-deposited state the responsivity decreases substantially for wavelengths below 500 nm compared to the theoretical predictions. This is attributed to a high recombination velocity at the silicon dioxide/silicon interface, as supported by computer simulations of the detector performance. In contrast, n +–p photodiodes are found to be rather insensitive with respect to the properties of the silicon dioxide/silicon interface. These results provide the first experimental demonstration that high built in electric fields, caused by abrupt dopant profiles, can suppress the influence of a high interface carrier recombination velocity.