Anomalous Scaling of Parasitic Capacitance in FETs with a High-K Channel Material

We investigate the operation of FETs with a high-K channel material, SrTiO
3
, (K=300). The transistors show low-leakage, high-capacitance operation with a sub-nm equivalent oxide thickness, in line with expectations. In depletion however, the gate-source capacitance appears to have an unusual 1/3power dependence on the device length and width. This awkward scaling behaviour is analyzed in detail in this paper and possible consequences for SrTiO
3
devices and related 2D-material transistors are discussed. It is argued to relate to the high-permittivity channel. This high permittivity is further experimentally shown to result in strong short-channel effects in $10-\mu \mathrm{m} -$long FETs, in spite of the highly scaled equivalent oxide thickness, when the operation temperature is lowered to 4.2 K.