D'yakonov-Shur instability in a ballistic field-effect transistor with a spatially nonuniform channel

The instability of a two-dimensional electronic liquid in the channel of a ballistic field-effect transistor is analyzed by investigating the energy b alance. A criterion of instability is found for arbitrary boundary conditio ns. Using energy-balance analysis we propose a device with a high instabili ty growth rate. The transistor possesses a spatially nonuniform channel and is analogous to a divergent channel in classical hydrodynamics. Our comput ed growth rate and threshold of the instability for this device agree with the computational data. (C) 1999 American Institute of Physics. [S1063-7826 (99)02005-0].