Current-Voltage characteristics of ungated GaAs FET's

• Published in: IEEE transactions on electron devices 1985-01, Vol.32 (11), p.2426-2430
• Main Authors: Junho Baek, Shur, M.S., Lee, K.W., Tho Vu
• Format: Article
• Language: English
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/T-ED.1985.22290

We develop a model which describes the current-voltage characteristics of GaAs saturated resistor loads (or ungated FET's) with uniform and nonuniform (ion-implanted) doping profiles. The results of the calculation are in good agreement with the experimental data for 1-, 2-, and 3-µm GaAs ungated FET's. Our model allows us to determine the values of the electron saturation velocity ν s and of the surface built-in voltage V Sbi from the measured current-voltage characteristics of ungated loads. For long devices (with 3-µm length) we obtain \nu_{s} \approx 1.20-1.21 \times 10^{5} m/s and V_{Sbi} \approx 0.46-0.47 V, in good agreement with expected values. For shorter (1 µm) devices, the measured values of ν s are considerably higher (1.64-1.73 × 10 5 m/s). This may be considered as evidence of velocity enhancement in short structures due to ballistic or overshoot effects.