Temperature dependence of Al/undoped Al0.5Ga0.5As/GaAs capacitors

• Published in: IEEE transactions on electron devices 1984-09, Vol.31 (9), p.1164-1168
• Main Authors: Drummond, T.J., Fischer, R.J., Kopp, W.F., Arnold, D.J., Klem, J.F., Morkoc, H., Shur, M.S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Capacitance-voltage characteristics; Capacitors; Electronics; Exact sciences and technology; Gallium arsenide; Interfaces; Logic gates; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Temperature; Temperature measurement; Tunneling
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/T-ED.1984.21682

Undoped Al 0.5 Ga 0.5 As is used in place of the insulator layer in the fabrication of MIS-type capacitors with Schottky gates. The current-voltage and capacitance-voltage characteristics of the capacitors were measured as a function of temperature in the range 300-77 K. At high temperatures current is by thermionic emission over the barrier determined by the Schottky contact and the Al 0.5 Ga 0.5 As/ GaAs conduction band discontinuity. As the temperature is lowered, Fowler-Nordheim tunneling is observed at sufficiently large gate biases and at 77 K conduction is ohmic. Based on I-V and C-V data the electron accumulation layer density is estimated to be about 1 × 10 12 cm -2 at 77 K when the capacitor is positively biased. The results obtained indicate that for an appropriate choice of parameters it should be possible to fabricate MIS-like transistors suitable for high-speed operation at 77 K.