Ge Nanowire-based High Linearity RF Amplifiers

In response to the DARPA SBIR solicitation, Omega Optics Inc. will collaborate with professors Emanuel Tutuc and Sanjay Banerjee at the University of Texas at Austin developing the Ge-SixGe1-x core-shell nanowire based high linearity FETs, which is important to emerging DoD-critical applications such as wide-dynamic-range phase array radar or remote sensor network. Compared with homogeneous Si or Ge nanowires, transparent (negative Schottky) contacts are formed to the conduction channel and the dopant scattering is eliminated. Furthermore, core-shell Ge–Si NWs provide a higher mobility one-dimensional hole gas compared to Si NWs. In addition, core/shell NWs offer an attractive platform for FET fabrication with high-k dielectrics, as the Si-containing shell serves as a passivation layer for the high-k dielectric deposition. It is well known that the RF performance (such as device current and ON/OFF ratio) of NW FETs with undoped S/D is significantly limited by the contact and series resistances. We propose Ge-SixGe1-x core-shell NWFET with highly doped S/D with improved RF performance, Our preliminary results show two orders of magnitude higher current compared to NW FETs with nominally undoped S/D, as well as an improved ON/OFF current ratio and noise figure (NF).