TABLE OF CONTENTS Electron or hole transport in commercially available electronic devices is governed by various scattering mechanisms. On the other hand, devices based on coherent transport (transport without scattering) are still at the developmental stage. To understand the coherent length or dephasing length, let us first consider an electron that undergoes an elastic collision, where the initial, ? i( r, t), and final, ? f( r, t), wave functions (Mitin et al. 1999) are
| (7.180) |  |
where k and k' are the wavevectors before and after the scattering event. For elastic scattering, we have k = k', which means that the momentum is conserved, and A k' 2 is the probability of finding the electron with a wavevector k' after scattering. From Eq. (7.180), one can obtain ? f( r, t) 2 = ?( r) 2, which means that the spatial distribution remains independent of time after scattering. The incident and scattered wave functions can produce complex wave patterns, but one of the most important properties of elastic scattering is that the phase of the electron is not destroyed, or elastic scattering does not destroy the coherence of the electron motion even for a distance larger than the elastic mean free path.
After inelastic scattering, the electron wave function has different energy and time dependences according to the following:
| (7.181) |  |
The time-dependent component of the...
