High drain field impact ionization transistors as ideal switches.

Yuan, Baowei; Chen, Zhibo; Chen, Yingxin; Tang, Chengjie; Chen, Weiao; Cheng, Zengguang; Zhao, Chunsong; Hou, Zhaozhao et al. · Nat Commun · 2024

basic_science · Level V

Where this comes from

Abstract

Impact ionization effect has been demonstrated in transistors to enable sub-60 mV dec<sup>-1</sup> subthreshold swing. However, traditionally, impact ionization in silicon devices requires a high operation voltage due to limited electrical field near the device drain, contradicting the low energy operation purpose. Here, we report a vertical subthreshold swing device composed of a graphene/silicon heterojunction drain and a silicon channel. This structure creates a low voltage avalanche impact ionization phenomenon and leads to steep switching of the silicon-based device. Experimental measurements reveal a small average subthreshold swing of 16 µV dec<sup>-1</sup> over 6 decades of drain current and nearly hysteresis-free, and the operating voltage at which a vertical subthreshold swing occurs can be as low as 0.4 V at room temperature. Furthermore, a complementary silicon-based logic inverter is experimentally demonstrated to reach a voltage gain of 311 at a supply voltage of 2 V.