3D Time-of-flight distance measurement with custom - Universität ...

SOLID-STATE IMAGE SENSING 65
Figure 3.12 Mobility, lifetime and diffusion length of minority carriers versus
impurity concentration in silicon. [SZ1, WON].
Drift in an electric field
When an electric field E is applied to a semiconductor sample, each electron will
experience a force -q⋅E from the field and will be accelerated along the field (in the
opposite direction) until it comes to a collision with the lattice atoms or impurity
atoms. An additional velocity called the drift velocity will therefore be superimposed
upon the random thermal motion of electrons. For low electrical fields E this mean
drift velocity vn of free electrons is given by:
vn n
= −µ
⋅ E
Equation 3.10