As a HEMT channel is formed by heterolayers with typical channel widths of 10 nm-20 nm, a highly quantum mechanical situation is
encountered. The typical geometrical width is smaller than the de Broglie length of 26 nm in GaAs,
as pointed out by Shur in [257] and also given in Appendix B.
This work treats the channel in a classical approach. This section
supplies some basic estimates of the error introduced with respect
to the material systems used. Based on the stationary *Schrödinger* equation

typically a one-dimensional analysis is performed. With no voltage applied a very precise analysis can be performed, as e.g. in [70,318]. A fully quantum mechanical two-dimensional analysis is rendered complicated due to the boundary conditions required [1].

2001-12-21