Answer Happy

4) Assume a thin film MESFET Pinch off voltage, Va, is given buy V> = (30) a? 2ND 2 EEO (4) Where a is the depletion width (W) required to completely deplete the conducting channel of the device. For a thin film MESFET, a would be equal to the thin film thickness t for a normally on thin film MESFET with gate length L as shown in Fig. (2). Till Source Gate Drain Ohmic Ohmic Schottky n-type GaAs L Semi insulating substrate Figure 2: Thin film MESFET t 1 Assume all data was generates from this MESFET wafer which is known to have an epilayer thickness of t = 0.2um. 13/2 VG - Vbi 21-(V6 - V0)] Ipsat = G. V + + V 3 VO 3

2 2 [Vo - (VG - Vbi) *** 1914-1) 1 V 21-(VG - V.] 10(V) = GV + V3 V D --- 3 and 2 a z G = PL Assuming the Z/L ratio is 50, determine, for a zero gate bias: Vpi Goi Iosat and Vosat 5) If the gate length for the above MESFET is L = 2um, what is the gate capacitance of this MESFET.