Cryogenic operation of static induction (SIT/SITh) devices

Detailed measurements and modeling of a 200 V, n-channel SIT with a vertically walled gate structure and a 500 V, asymmetrical planar gate SITh in the 300 to 77 K temperature range are described for the first time. When the temperature is reduced from 300 to 77 K, it has been observed that: maximum blocking voltage in these devices decreases by 20%; DC blocking gain increases slightly, a 7.5× reduction in forward drop occurs for the SIT while a 40% increase in the knee voltage and a dramatically improved I-V slope occurs at high current densities for the SITh; and during gate turn off of the SITh, a 95× and 10× reduction in extracted gate charge and turn off time occurs, respectively. The SITh forward drop vs turn off time trade off curve obtained by temperature reduction is much superior to that obtained by electron radiation