Design and reliability assessment of an ultra-thin body electrostatically doped bipolar transistor for mixed signal applications

Abstract

Shrinking of the thickness of silicon on insulator (SOI) has been proposed as a potential solution for scaling down the physical base length of symmetric lateral electrostatically doped bipolar transistors. An ultra-thin body device that utilizes the full SOI thickness has been presented and the performance of the same is investigated in detail. The device features two distinct doping techniques: work function-induced electrostatic doping (WED) and bias-induced electrostatic doping (BED). The proposed design approach leads to significant improvements in gain and cut-off frequency compared to previously reported designs. The resulting devices exhibit peak current gain $\beta$ values $>1100$, $f_t>500$ GHz, $f_{max}>1300$ GHz. Moreover, these improved device performance matrices get translated into better performance of universal gates with low rise and fall time of $\sim 1.3$ ns, and improved noise margin performance in static random access memory (SRAM) device of 0.43 and 0.41 for WED and BED based devices respectively. Furthermore, the study investigates the reliability of the device concerning breakdown voltage and its response to different temperature conditions. The findings reveal a decline in the $\beta$ value for WED-based devices when subjected to temperatures exceeding $340$ K. In contrast, BED-based devices demonstrate a comparatively smaller variation in $\beta$ at temperatures above $340$ K. These results show the potential of the proposed device for mixed-signal and digital circuit applications.