Ballistic Quantum Transport in Terahertz Indium Gallium Nitride C-Plane and A-plane High Electron Mobility Transistors

This paper presents numerical calculations of ballistic quantum transport in c-plane and a-plane indium gallium nitride high electron mobility transistors (HEMTs). We calculate quantum mechanical transit times across the channel region of the HEMT and take into account spontaneous and piezoelectric polarization in these materials. Unity gain frequencies of 2.8 terahertz are achievable using nanoscale device dimensions. Ballistic gate lengths of 10.8nm-15nm are obtained from quantum transport calculations. A-plane transistors are able to achieve normally-off HEMT operation due to elimination of spontaneous and piezoelectric polarization effects. A-plane transistors also offer higher immunity to gate-drain leakage and to stress-related barrier reliability issues. We explicitly take into account the effect of longitudinal optical ( LO ) phonon scattering rates on the ballistic device dimensions. Our calculations show that plasmon collective oscillations do not substantially affect the device dimensions in terahertz and near-terahertz regimes for typical device parameters in this material system. We also explicitly study the effect of indium percentage in the indium gallium nitride channel on device characteristics like unity gain frequencies and current densities.