[paper] Nanoscale InGaAs FinFETs

Jesús A. del Alamo1, Xiaowei Cai1,2, Xin Zhao1, Alon Vardi1, and Jesús Grajal3

Nanoscale InGaAs FinFETs: Band-to-Band Tunneling and Ballistic Transport

51st European Solid-State Device Research Conference, Grenoble 2021

   
1: Microsystems Technology Laboratories, MIT, Cambridge (USA)
2: Analog Devices, Inc., (USA)
3: IPT Center, Universidad Politécnica de Madrid (SP)

Abstract: InGaAs is an attractive material for high-speed, high-frequency electronics and ultra-low-noise applications. A great effort has taken place recently towards the development of high-performance InGaAs MOSFETs with different geometries: planar MOSFETs, FinFETs and Nanowire MOSFETs. This exploration has uncovered a number of interesting device physics of relevance to the development of electronics based on other material systems. InGaAs is a narrow bandgap material. As such, it is prone to excess band-to-band tunneling at moderate voltages. Due to the floating nature of the InGaAs MOSFET body, holes generated by BTBT cannot escape from the body. Through a parasitic lateral bipolar transistor that is hiding inside the MOSFET, this results in excess off-state current, which compromises transistor logic operation. InGaAs also features a very small effective mass. This yields prominent ballistic effects in nanoscale devices. Towards studying this, we have developed a new technique to extract mobility and injection velocity in InGaAs MOSFETs in the presence of severe gate oxide trapping, as is the case in the high-k/InGaAs MOS system. In InGaAs FinFETs, we find a degradation in scattering limited mobility but an enhancement in ballistic mobility as the fin-width narrows. Also, the injection velocity shows no discernable fin width dependence. An important lesson from these studies is that long channel mobility measurements constitute a poor predictor of short-channel performance of InGaAs FinFETs.

Fig: Cross section of self-aligned InGaAs FinFETs on InP (left) along and (right) across the fin. The intrinsic channel is In_0.53Ga_0.47As and it is nominally undoped. These are double-gate devices.

Acknowledgment: Research sponsored by DTRA (#HDTRA 1-14-1-0057), NSF (E3S STC Award 0959514), MISTI, KIST and Lam Research. Devices fabricated in MIT’s Microsystems Technology Laboratories and EBL.