Mobility profiles in short and narrow GaAs MESFET channels

Gate-voltage-dependent mobility profiles in long-, short-, wide-, and narrow-channel WN/sub x/-BPLDD (buried p-type buffer lightly doped drain region) GaAs MESFETs have been determined (L/sub G/=10, 4, 2, 1, 0.8, 0.5, 0.3 mu m, W/sub G/=20 mu m; W/sub G/-100, 40, 20, 10, 4, 2 mu m, L/sub G/=0.5 mu m). The mobility mainly depends on the channel width, while the gate length has much less influence. Thus, using proper gate dimensions the channel mobility can be tuned. The highest drift mobility values agree quite well with the measured Hall mobilities. Mobility profiles of large-area MESFETs are probably degraded by the WN/sub x/-gate fabrication process. Injected excess charges at gate length below 0.5 mu m distorts the mobility evaluations.<
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