Ballisticity of the linear response transport in nanometric silicon devices

In modern devices the electron current flows through space charge regions, which are about 20 nm thick. Such thin space charge regions can be obtained only by very high doping concentrations, which lead to strong built-in fields. Similarly, an applied bias leads to a strong electric field in the space charge region and the transport in this is known to be quasi ballistic. Based on a deterministic solver for the Boltzmann equation the linear response of the distribution function has been calculated. It is found that the linear response contains a ballistic part, which is due to the strong built-in fields in nanometric devices.