Irradiation of optically activated SI-GaAs high-voltage switches with low and high energy protons
- Univ. Federico II and INFN, Napoli (Italy). Dipt. di Scienze Fisiche; and others
Semi-Insulating Gallium Arsenide (SI-GaAs) devices have been tested for radiation hardness with 3--4 MeV or 24 GeV proton beams. These devices can be operated in dc mode as optically activated electrical switches up to 1 kV. Both single switches (vertical Schottky diodes) and multiple (8) switches (planar devices) have been studied, by analyzing their current-voltage (I-V) reverse characteristics in the dark and under red light illumination, both before and after irradiation. The authors propose to use them in the system of high-voltage ({minus}600 V) switches for the microstrip gas chambers for the CMS experiment at CERN. Low energy protons (3--4 MeV) were used in order to produce a surface damage below the Schottky contact; their fluence (up to 2.6 {times} 10{sup 15} p/cm{sup 2}) gives a high-dose irradiation. The high energy proton irradiation (energy: 24 GeV, fluence: 1.1 {times} 10{sup 14} p/cm{sup 2}) reproduced a ten years long proton exposure of the devices in CMS experiment conditions. For low energy irradiation, limited changes of the I-V curves in the dark have been observed, with at most a fourfold increase of the leakage current; after exposure, however, the breakdown voltage decreases significantly. For high energy irradiation, the authors observed--for the vertical Schottky diodes biased at {minus}600 V--an increase of the leakage current and a reduction of the photocurrent after irradiation, with respect to pre-irradiation conditions. For these diodes, the reduction of the photocurrent/dark current ratio was 25:1. At the same proton energy, an analogous behavior was shown by the planar devices, but after irradiation the current gain may reduce over three orders of magnitude.
- OSTI ID:
- 679541
- Report Number(s):
- CONF-981110-; ISSN 0018-9499; TRN: 99:009473
- Journal Information:
- IEEE Transactions on Nuclear Science, Vol. 46, Issue 3Pt1; Conference: 1998 IEEE nuclear science symposium and medical imaging conference, Toronto (Canada), 10-12 Nov 1998; Other Information: PBD: Jun 1999
- Country of Publication:
- United States
- Language:
- English
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