Compact Behavioral Modeling and Time Dependent Performance Degradation Analysis of Junction and Doping Free Transistors

The junctionless as well as dopingless field effect transistor (JLFET) can be a potential candidate for future CMOS technology due its innate properties, such as simplified fabrication process, low thermal budget and better immunity towards process variations. In this paper, time dependent performance degradation (or temporal variations due to silicon aging) of Common Source (CS) amplifier designed with conventional and dopingless JLFETs has been investigated for channel hot carrier (CHC) stress under different time spans. The time dependent performance degradation of both devices was compared at device as well as circuit level. The compact behavioral Verilog-A models of both devices have been developed that capture the DC as well as transient behavior accurately for circuit level analysis. From our proposed device-circuit co-simulations approach, we observed that the voltage gain of a CS amplifier based on conventional JLFET is degraded by 20.2% and 32.6% due to CHC stress of 2000 seconds and 6000 seconds, respectively. However, the dopingless JLFET experiences 8.5% to 13.2% degradation for the same time span. Similarly the phase shift, output resistance and transconductance of the CS amplifier are also degraded due to CHC stress for JLFET more severely than dopingless JLFET.

I. Introduction

The ever increasing need for energy-efficient and highperformance systems has driven the device scaling trends for last few decades [1]–[3]. As a result, nanoscale devices with shrinking dimensions as well as different architectures have been explored for design of energy-efficient and fast integrated circuits and systems. The junctionless field effect transistor (JLFET) has emerged as a strong candidate to replace the conventional metal oxide semiconductor field-effect transistor (MOSFET) due to its simplified fabrication process, adequate current-driving capability to meet modern requirements, and better immunity to short-channel effects (SCEs) [4]. However, innate properties of the JLFET such as high gate work function metal requirement to deplete the heavily doped channel, and impact ionization phenomenon due to high electric field in the channel near the drain region causes time dependent performance degradation. This high electric field generates energetic electrons and holes that get injected into the gate dielectric near to drain region, hence it causes interface states.