Effect of high field electron transport characteristics on transistor performance in InGaAs/InAlAs heterostructures

We have studied electron transport in a variety of doped and modulation-doped InGaAs/AlInAs quantum wells within the context of FET performance in devices fabricated from the same structures. Electron velocities in the structure were characterized using Hall, geometric magnetoresistance, and high-frequency velocity-field measurements. Peak velocities of 1.5/spl times/10/sup 7/ cm/s were measured for various delta-doped wells, while a peak velocity of 2.0/spl times/10/sup 7/ cm/s was measured for the MODFET structure. The effect of various well widths on the transport characteristics was also studied. FETs with 1.8 /spl mu/m gate lengths and uniformly doped channels had transconductances of 267 mS/mm while the MODFET had g/sub m/=338 mS/mm. MODFETs with 0.5 /spl mu/m gates yielded g/sub m/=590 mS/mm. In general, device performance was well correlated to the peak electron velocity and only somewhat correlated to the low-field mobility.<
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