Characteristics of 0.8- and 0.2-μm gate length InxGa 1-xAs/In0.52Al0.48As/InP (0.53⩽x⩽0.70) modulation-doped field-effect transistors at cryogenic temperatures

The performance characteristics of InP-based pseudomorphic MODFETs with varying the In composition (0.53⩽x⩽0.70), which changes the strain in the channel, were studied. The temperature was varied in the range of 40-300 K, and the devices had gate lengths L _g of 0.8 and 0.2 μm. The analysis predicts an increase in the intrinsic cutoff frequency with increasing In composition and decreasing temperature and gate length. Also, the analysis predicts that the increase in cutoff frequency with decreasing temperature is less significant with increasing In composition and decreasing gate length. Preliminary experimental results show that as In composition increases from 0.53 to 0.70, f_T increases by 30-40%, and as the temperature decreases from 300 to 40 K, f_T improves by 15-30%, both for 0.8- and 0.2-μm devices