**This post gives an introduction into static induction transistors. Static induction devices (SID) are transistors operating with a prepunch-through region. These devices feature outstanding operating characteristics, with frequencies up to 1THz, and have great switching speed, low switching energy, large reverse voltage and low forward voltage drop.**

*static induction transistor*(SIT). These can be seen schematically in Figure 1. The operational idea of an SID is that it electrostatically induces a potential barrier in the device and can control the current between the drain and source. For an SID, where a small electrostatic field exists in the region of the potential barrier, the current through the device (drift and diffusion) can be described as: ${J}_{n}=\frac{q{D}_{n}{N}_{S}}{{\int}_{{x}_{1}}^{{x}_{2}}exp(\u2013{\displaystyle \frac{\phi \left(x\right)}{{V}_{T}}})dx}$. Here ${N}_{S}$ is the carrier concentration for ${x}_{1}$.

The potential along the static induction transistor channel and across the transistor channel can be described relatively with the function of the second order. $\phi \left(x\right)=\Phi \left[1\u2013(2\frac{x}{L}\u20131{)}^{2}\right]$, and $\phi \left(x\right)=\Phi \left[1\u2013(2\frac{y}{W}\u20131{)}^{2}\right]$ for two channel dimensions, here $\Phi $ is the height of the potential barrier. The drain current through the transistor will be ${I}_{D}=d{D}_{p}{N}_{S}Z\frac{W}{L}exp\left(\frac{\Phi}{{V}_{T}}\right)$. Here ${N}_{S}$ is the concentration of the source, $\frac{W}{L}$ are the geometrical characteristics of the potential saddle of the barrier. Here the potential $\Phi $ is always a function of the gate and drain voltages.

Currents in the static induction transistors are controlled with the other characteristics – the space charge of the charge carriers.

SITs can be used to obtain the SID. These diodes have a low forward voltage drop. This diode can be made by shortening the emitter to the gate of the SIT (Figure 2).

Figure 2.