Channel Thickness Dependence of InGaAs Quantum-Well Field-Effect Transistors With High- $\kappa$ Gate Dielectrics

We have studied channel thickness dependence of InGaAs quantum-well field-effect transistors (QWFETs) with high-κ gate dielectrics. Device performances of ultrathin 5- and 10-nm-channel In_0.7Ga_0.3As QWFETs with gate length down to sub-50-nm regime have been investigated. Thinning down the channel improves subthreshold characteristics and reduces the short-channel effect. The 5-nm In_0.7Ga_0.3As channel (Lg = 40 nm) devices exhibit a reduced subthreshold swing (SS) of around 100 mV/dec and drain-induced barrier lowering (DIBL) of 128 mV/V compared to 10-nm In_0.7Ga_0.3As channel devices (SS of ~ 140 mV/dec and DIBL of ~ 275 mV/V). However, the drawback for thinner channel devices is that the effective channel mobility also decreases. At inversion charge density of 3 ×10¹²/cm², 10-nm In_0.7Ga_0.3As channel devices exhibit mobility of 1860 cm²/V·s versus mobility of 1460 cm²/V·s for 5-nm In_0.7Ga_0.3As channel devices.