An optically activated diamond field effect transistor

• Published in: Diamond and related materials Vol. 8; no. 2; pp. 946 - 951
• Main Authors: Lansley, S.P, Looi, Hui Jin, Whitfield, M.D, Jackman, R.B
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-1999
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/S0925-9635(98)00423-3

Thin film diamond photodetectors are one of the most promising classes of diamond devices for commercial exploitation. Already, photoconductive devices which display extremely high levels of selectivity between deep UV and visible light, allied to good sensitivity, are becoming available. However, more advanced device designs are required if high speed operation is to be achieved alongside high sensitivity. Phototransistors are ideally suited to this application, but until recently room temperature operation of diamond field effect transistors (FETs) was not possible. This has changed with the emergence of p-type hydrogenated diamond and this paper describes the fabrication and operation of the first MESFET based diamond photodetectors (OPFETs) to be made. Optical modulation has been demonstrated and the wavelength selectivity measured. Devices respond significantly more to UV light than visible wavelengths, with gain levels of around 4. The mechanism(s) of operation are discussed.