Device Physics of Vertical Static Induction Transistors

Vertical static induction transistors (SITs), with vertically arranged source, porous gate, and drain electrodes, were proposed in 1950s and have recently gained new attention because of their suitability as flexible substrates and for hybrid integration with light-emitting diodes. However, the understanding of them is hindered by Schottky gate leakage and relies on case-by-case simulations. Here, we derive concise expressions for the channel potential and current-voltage characteristics for ideal SITs, including the subthreshold swing, threshold voltage, and above-threshold region. The theory is verified by two-dimensional device simulation and agrees well with the reported experimental results. An ideal SIT can be approximated as a partially gated transistor in parallel with a resistance and needs a sub-500-nm pore diameter to exhibit sharp switching in transfer scanning and good saturation in output scanning. The proposed theories connect the device structure and electrical characteristics of SITs concisely, and conclusions are also applicable to permeable base transistors.