Tunneling field-effect transistor with Ge/In0.53Ga0.47As heterostructure as tunneling junction
Chia, Ching Kean
Date of Issue2013
School of Physical and Mathematical Sciences
High quality epitaxial germanium (Ge) was successfully grown on In0.53Ga0.47As substrate using a metal-organic chemical vapor deposition tool. The valence band offset ΔEV between the Ge layer and In0.53Ga0.47As determined by high-resolution x-ray photoelectron spectroscopy was found to be 0.5 ± 0.1 eV, suggesting the Ge/In0.53Ga0.47As heterojunction has a staggered band alignment at the interface. This makes the Ge/In0.53Ga0.47As heterojunction a promising tunneling junction for application in tunneling field-effect transistor (TFET). Lateral TFET with in situ doped p+ Ge-source In0.53Ga0.47As-channel using a gate-last process was demonstrated for the first time. The temperature dependence of the TFET transfer characteristics was investigated. The TFET with gate length (LG) of 8 μm exhibits an on-state tunneling current (ION) of 380 nA/μm at VGS = VDS = 2 V. The subthreshold swing (S) at the steepest part of the transfer characteristics of this device is ∼177 mV/decade. It was found that the off-state leakage current (IOFF) was determined by the Shockley-Read-Hall generation-recombination current in the Ge-source region. The temperature dependence of ION was mainly due to the change of the band gap with temperature. Furthermore, S was found to be limited by the trap-assisted tunneling at the Ge/In0.53Ga0.47As tunneling junction. The low ION and poor S can be enhanced by improving the source/channel profile and optimizing Ge epitaxial growth process.
Journal of applied physics
© 2013 American Institute of Physics. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The paper can be found at the following official DOI: [http://dx.doi.org/10.1063/1.4794010]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.