Chemistry Reference
In-Depth Information
where and are the capture coefficients for electrons and holes at the surface,
is the concentration of surface states, and are the concentra-
tions of electrons and holes at the surface with and the concentrations at equilib-
rium, and are the concentrations of captured electrons and holes in the surface
states, and is the degree of filling of the surface states. In the steady state,
and Eqs. (1.99) and (1.100) become
where For a nondegenerated material, suppose that (1) quasineutral-
ity is fulfilled at the boundary of the space charge layer,
so that the concentra-
tions of excess electrons and holes are equal
and (2) the departure from
equilibrium is insignificant, that is,
then the surface recombination
velocity, which is defined as
can be obtained from Eq. (1.101) as
The recombination velocity, which characterizes the recombination process, may vary
over a wide range, from 1 to at room temperature.
962
Surface recombina-
tion centers that can be described by the one discrete recombination center model have
been found to exist in different silicon/electrolyte systems.
61,182,278,808
The states that
can exchange charge carriers with only one of the bands are traps for electrons or
holes. Surface states that contribute to the interface capacitance but do not act as the
