Quantum well and III-V electronics

Hole Mobility in Si Ultra-Thin Layers

•Understand the influence of confinement length scale and confinement direction and transport orientation on carrier mobility in ultra-thin Si layers
•Use the sp3d5s*-SO tight-binding model for electronic structure calculation and linearized Boltzmann transport theory
•The electronic structure is a strong function of geometry at the nanoscale
•For holes, the (110)/[110] channels are highly advantageous compared to other configurations
•(110) surfaces have a larger hole confinement effective mass and are more tolerant to surface roughness scattering

Quantum transport in III-V HEMTs for High Performance Logic Applications

Quantum transport in III-V HEMTs for High Performance Logic ApplicationsObjective:
• Understand experimental data on III-V HEMT devices for logic applications
• How close to the ballistic limit are short channel III-V devices
• What controls their performance
• Use a 2D quantum (NEGF) simulator
• Simulate the experimental structure using delta-doped doping
• Use the sp3d5s* TB model to extract the effective mass of the III-V channel
• Devices as short as LG=60nm are close to the ballistic limit
• The series resistance Rsd and the design of the contacts affects the performance
• Identified the low doping in the contacts as the most possible reason for the Gm degradation observed in experimental data
•Gm rolls off as the gate bias increases, possibly due to source exhaustion