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

Abstract

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 1.5×107 cm/s were measured for various delta-doped wells, while a peak velocity of 2.0×107 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 μm gate lengths and uniformly doped channels had transconductances of 267 mS/mm while the MODFET had gm = 338 mS/mm. MODFETs with 0.5 μm gates yielded gm = 590 mS/mm. In general, device performance was well correlated to the peak electron velocity and only somewhat correlated to the low-field mobility.