A Simulation Perspective: The Potential and Limitation of Ge GAA CMOS Devices

The electrical characteristics of n/p Ge nanowire transistors (NWTs) with the cross section of $6\times 6\mathrm{n}\mathrm{m}^{2}$ have been studied. The ION performance and the subthreshold swing are simulated by multi-subband Boltzmann transport equation and ballistic quantum transport solvers, respectively. The performance of nGe NWTs is sensitive to the barrier height of interfacial layer due to highly-anisotropic $\Lambda$-valleys. The dimension-dependent k·p parameters based on tight-binding full band are used to address the strong confinement of pGe NWTs. Comparing to Si NWTs, the intrinsic I ON is twice as high for both n/p Ge NWTs at 28nm channel length. As the channel length is scaled down, such ION benefit is maintained till the tunneling effect comes in and degrades the subthreshold swing.