Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 73: Devices
HL 73.1: Talk
Thursday, March 14, 2013, 09:30–09:45, H15
Does Scaling help making HEMTs faster? — Sabbir Ahmed1, Kyle David Holland1, Navid Paydavosi1, Christopher Martin Sinclair Rogers1, Ahsan Ul Alam1, Neophytos Neophytou2, •Diego Kienle3, and Mani Vaidyanathan1 — 1Department of Electical and Computer Engineering, University of Alberta — 2Institute for Microelectronics, Technical University of Vienna — 3Theoretische Physik I, Universität Bayreuth
The scaling-down of channels has been the basis to design faster transistors. Particularly III-V high-electron-mobility transistors (HEMTs) have been favored for terahertz applications thanks to their low-effective mass. However, experimentally it is known that the unity-current gain and power-gain cut-off frequencies (fT and fmax) of HEMTs exhibit the tendency to saturate with shorter channel lengths and thus become insensitive to scaling. In this talk we employ a self-consistent, quantum-mechanical NEGF solver to quasi-statically extract the fT of intrinsic III-V devices, focusing on InGaAs and GaN HEMTs with channel lengths of 50 nm down to 10 nm. We show that the non-scaling behavior of HEMTs is a result of short-channel effects (DIBL) leading to a weaker quantum confinement, so that the subbands are positioned lower in energy resulting in a larger-than-expected charge modulation and gate capacitance, respectively. It is also shown that the InGaAs HEMTs have faster fT at long gate lengths, but as a consequence of their lower effective mass, they experience a more rapid fT saturation than the GaN HEMTs, such that the two devices have a comparable fT at very short gate lengths down to 10 nm.