Geometrical and light-induced effects on back-gating in ion-implanted GaAs MESFET's

• Published in: IEEE transactions on electron devices 1985-01, Vol.32 (1), p.28-33
• Main Authors: Subramanian, S., Bhattacharya, P.K., Staker, K.J., Ghosh, C.L., Badawi, M.H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Current measurement; Electronics; Exact sciences and technology; Gallium arsenide; Integrated circuits; Logic gates; MESFETs; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Substrates; Transistors; Voltage measurement
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/T-ED.1985.21904

Back-gating effects in GaAs MESFET's have been studied for small (10-30 µm) and large (~150 µm) back-gate separations and for different geometric positions of the back-gate. It is found that the substrate currents just at the onset of back-gating and when the channel is pinched off by the gate voltage are independent of the proximity of the back-gate. The geometric position of the back-gate is found to have a very strong influence on the back-gating characteristics. Illumination of the devices with white light gives rise to large substrate currents even for small back-gate voltages, and thus hastens the onset of back-gating. A simple qualitative model is presented to explain the observed results. Deep-level traps in the substrate, channel-substrate interface, and the channel have been studied by observing the drain current transients induced by a pulsed back-gate voltage or by a pulsed front-gate voltage. In addition to the EL2 electron trap with activation energy 0.82 eV detected in the substrate, a nondiscrete band of interface traps have been identified.