Two dimensional hole gas (2DHG) germanium junctionless P-FinFETs without impurity scattering achieved by modulation doping in channel

Abstract

For the junctionless field-effect transistors (JL-FETs), there is a big concern that the high channel doping degrades carrier mobility by ionized impurity scattering mechanism. In this work, a sandwiched Ge/GeSi/Ge layer structure is proposed to be used as JL-FinFET channel, and only the middle GeSi layer is modulation doped by B atoms. In this structure, two dimensional hole gas (2DHG) forms in the top and bottom Ge channel layers, and is separated from B dopant impurity in the middle GeSi layer. Due to high hole mobility of 2DHG, the device exhibits an enhanced on-state current. The finished 2DHG Ge JL-FinFET shows a 6× current enhancement as compared to controlled Ge JL-FinFET with a uniformly B-doped Ge channel.