Lecture III.

. Transient and Steady-state Photoconductivity in Insulators, Theory and Experiment Small-signal limit Drift Mobility

Trapping (shallow and deep)

Transient photoconductivity- determination of the drift mobility

For an applied electric field constant in position and time, E=V/d, where V is the applied

potential across the photoconductor, and d its

thickness.

Let v be the drift velocity, and μ be the carrier mobility, so, by

definition, μ=v/E

When the carriers reach the back electrode (x=d), time is their-time-

of-flight t. Then μ= (d/t)/(V/d)

Carrier Trapping

Shallow Traps

Deep Traps