A temperature dependent model for the saturation velocity in semiconductormaterials

Precise modeling of the saturation velocity is a key element for device sim ulation, especially for advanced devices such as e.g. High Electron Mobilit y Transistors (HEMTs) where the saturation velocity v(sat) is directly rela ted to the available gain of the device. We present a model implementing th e temperature dependence of the saturation velocity v(sat) into the two-dim ensional device simulator MINIMOS-NT. The new model covers all relevant mat erials such as the elementary semiconductors Si and Ge, and the binary III- V group semiconductors GaAs, AlAs, InAs, GaP and InP. Furthermore, a compos ition dependent modeling for alloyed semiconductors such as e.g. Si1-xGex, AlxGa1-xAs or InxGa1-xAs is included. The implementation reflects a compreh ensive literature survey on available experimental data and Monte Carlo (MC ) simulation data. The work is completed by new MC simulations, especially for material compositions, where no experimental data are available. The ex traction of the saturation velocity reveals a significant difference betwee n the saturation velocity in the bulk and the effective (saturation) veloci ty extracted from rf-measurements e.g. for High Electron Mobility Transisto rs. Since this effective value is often used for device characterization, t he difference gives insight into modeling the determining quantities of HEM Ts. (C) 2000 Elsevier Science Ltd. All rights reserved.