Impact Ionization in Junctionless Field‐Effect Transistors

This chapter analyzes impact ionization and its effect on the performance of the JLFETs. The different architecture of junctionless field‐effect transistors (JLFETs) as compared to the conventional metal‐oxide‐semiconductor field‐effect transistors (MOSFETs) leads to an altogether different behavior with respect to the onset of impact ionization induced steep subthreshold swing. This leads to several interesting physical phenomenon in JLFETs such as occurrence of a zero gate oxide thickness coefficient and single transistor latch‐up, which open up a new horizon for application of JLFETs in memories such as capacitorless dynamic random access memory (DRAM) and as biosensors. The chapter discusses in detail the physical essence of the impact ionization phenomenon and analyzes its implications on the JLFETs. The impact ionization induced steep switching in JLFETs is attributed to the enhanced bipolar effects. Ion bombardment in MOSFETs leads to the generation of electron‐hole pairs (EHPs) in the channel region, which may create additional EHPs due to impact ionization.