A model predicting sheet charge density and threshold voltage with dependence on interface states density in LM–InAlN/GaN MOSHEMT

Trap densities in oxide/semiconductor interface are very crucial factor in deciding the performance of HEMT devices. Its effect cannot be overlooked which though have negligible effect below a particular value can degrade the performance of the device at higher values. In this regard a model is presented relating important parameters like surface potential, sheet charge concentration and threshold voltage in relation to the number of density of states in lattice matched (LM) In$_{0.17}$Al$_{0.83}$N/GaN based MOSHEMT. The model explains phenomena like current collapse and surface potential pinning which further leads to threshold voltage pinning that can lead to serious problems in HEMTs. An insight on the preference of metal to be used as a gate metal is also provided.