Exploring the Designs of p-Type Piezoelectric FinFETs Based on NEGF Transport Simulations Comprising Phonon Scattering

Abstract

We propose two different designs of p-type piezoelectric (PE) FinFETs (PE-FinFETs) covering low-power (LP) and high-performance (HP) operation modes. LP mode PE-FinFETs achieve a lower OFF-current ( ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ ) and HP mode PE-FinFETs result in a larger ON-current ( ${I}_{ \mathrm{\scriptscriptstyle ON}}$ ). These two different modes are achieved by simply changing the outer PE-gates bias. The advanced nonequilibrium Green’s function (NEGF) approach self-consistent with six-band ${k}\cdot {p}$ method including phonon scattering is used to investigate the device performance. The gate voltage-controlled strain is analytically derived from the principle of PE effect. The HP and LP PE-FinFETs are studied, respectively, and the impacts of channel material, device orientation, and phonon scattering on both HP and LP PE-FinFETs are comprehensively investigated. The simulation results show that Ge is superior to Si for both LP and HP PE-FinFETs. With a supply voltage of 0.5 V, ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ of Ge LP mode PE-FinFETs is reduced by 18 times, and Ge HP mode PE-FinFETs obtain 50% ON-current enhancement. ${I}_{ \mathrm{\scriptscriptstyle ON}}$ ( ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ ) is unchanged for LP (HP) mode PE-FinFETs. Phonon scattering not only causes a large ${I}_{ \mathrm{\scriptscriptstyle ON}}$ degradation but also changes the optimal device orientation for both Si and Ge HP mode PE-FinFETs compared to their counterparts without phonon scattering.