Single Event Transient Effects in Nano Scaled Devices and Circuits

Abstract

When the electronic systems are operated in radiation environment such as space, newlinethe devices and circuits deviate from their expected behaviour leading to malfunction.Single-event transient (SET) is one of the radiation effects that happens when an ionizing particle like heavy-ion strikes the sensitive region of MOSFET such as reversebiased P-N junction. This SET causes a transient current spike at the output of struck device creating a voltage transient. The effect of such a transient voltage pulse or spike is that it will propagate through the logic gate circuitry and can be latched in a memory element such as flip-flop (FF) as an erroneous logic state. This erroneous logic state corrupts the output of designed application. So a thorough understanding of the radiations effects in devices and circuits is of great importance. In this thesis, the radiation effects in nanoscale devices and the impact in circuits such as delay locked loop (DLL) and time-to-digital converter (TDC) are studied. The thin buried oxide (BOX) and ground plane (GP) combination in SOI MOSFET will aid technology scaling. The effect of this combination with respect to heavy-ion irradiation is studied. The comparison of radiation response of bulk and SOI based two stage inverter and then the inverter chain is analysed. The results show that the thin BOX with ground plane reduces the parasitic bipolar gain. Also the SOI based inverter has lesser SET pulse width than the bulk counterpart. The radiation analysis is carried out in DLL and TDC using a verilog-A based switch-and-resistor technique. The analysis shows that heavy-ion impact in DLL produces duty cycle and missing pulse errors, while in TDC, it produces widening and narrowing of time interval. A comparison of radiation resilience is also done between silicon-and carbon nanotube-based level shifters, with latter having better resilience.These analysis will be helpful for mitigating radiation effects in circuits to be operated in radiation environment newline