Topic: Schottky junction, SB-MOSFETs, Beyond MOSFETs
As gate length will be scaled down to under ~20nm, short channel effects have been significantly considered. In order to suppress short channel effects, body thickness (or junction depth) also will be scaled down to ~6nm. However, resistance in source/drain regions increases because of their thin body. Therefore, contact resistance reduction technology using Schottky junction is proposed.
A key for Schottky junction is Schottky barrier height (SBH). Generally, SBH is determined by Schottky-Mott rule. It predicts the SBH based on the work function of the metal relative to the electron affinity of the semiconductor. However, it was found experimentally that predicted SBH was wrong (Fermi-level pinning effect).
We have performed the first principle calculations (Density functional theory, DFT) to predict the SBH. For doing this job, optimized metal-semiconductor atom structures are necessary. With calculated SBH, we can investigate the performance of Schottky barrier (SB) MOSFETs.
Available DFT Tools: SIESTA, openMX
SB-MOSFETs are the most promising candidates as the future devices because of their low parasitic resistance and capacitance in source/drain region. However, low on-state current is major drawback due to their SBH. To enhance device performance in SB-MOSFETs, there are two ways: Reduction of SBH and improvement of carrier mobility.