| AVS 60th International Symposium and Exhibition | |
| Electronic Materials and Processing | Wednesday Sessions |
| Session EM-WeA |
| Session: | III-V Devices and Tunnel FETs |
| Presenter: | C.L. Hinkle, University of Texas at Dallas |
| Authors: | R. Galatage, University of Texas at Dallas C.L. Hinkle, University of Texas at Dallas E.M. Vogel, Georgia Institute of Technology |
| Correspondent: | Click to Email |
The measurement, modeling, and extraction of MOS relevant parameters from high-k on III-V semiconductors is significantly more challenging than that for Si gate stacks. Oxidation of the III-V material during high-k deposition leads to an extremely high interface trap density (Dit) as well as tunneling of carriers into defects further away from the interface. Additionally, the exact band structure of III-V semiconductors is a matter of ongoing research,1 and the effects of band non-parabolicity and quantization have not been thoroughly investigated. Each of these considerations is crucial in the proper analysis of III-V MOS devices.
Due to the high electric fields, quantum mechanical effects have a significant impact on the electrical properties of scaled MOS devices. In accumulation and inversion, quantization results in the splitting of the once continuous energy bands into discrete subbands and moves the charge centroid away from the semiconductor/dielectric interface. Both of these effects reduce the inversion and accumulation charge density at a given gate bias resulting in both a threshold and flatband voltage shift, as well as a reduction in the inversion and accumulation capacitances. Therefore, it is imperative that quantum mechanical effects be considered to accurately extract the EOT, Vfb, and Dit when researching these devices. Full Schrodinger/Poisson solvers are available to calculate the carrier concentration in a physically accurate and self-consistent manner. However, these calculations take considerable computation time and cannot be used to extract parameters from an experimental data set.
In this work, we implement quantum mechanical corrections to rapidly extract relevant III-V MOS C-V parameters by approximating the quantization effects as an effective increase in the semiconductor bandgap in accumulation and inversion in a manner similar to that of van Dort for Si.2,3 When coupled with non-parabolic energy bands, these approximations are shown to be quite accurate in modeling and extracting the characteristics of III-V/high-k devices. These approximations have been rigorously tested against experimental III-V devices as well as benchmarked with full Schrodinger/Poisson solutions to ensure their accuracy. This implementation allows for the rapid assessment of III-V parameters .
This work is sponsored by the SRC Global Research Corporation.
1 T. P. O'Regan, et al., Applied Physics Letter, 96,103705, 2010.
2 M. J. Van Dort, Solid-State Electronics, 37, 411, 1994.
3 E. M. Vogel, et al., Solid State Electronics, 47, 1589, 2003.