On the relation between threshold current and interface recombination velocities in double-heterojunction lasers

In a light-emitting double-heterojunction structure, interface recombination reduces the quantum efficiency of spontaneous emission
eta
; more specifically, in a double-heterojunction laser this increases the threshold current density J
th
. Simplified expressions are derived here for the dependence of
eta
and J
th
on interface recombination velocities in the injection regimes of both
n \ll p
(or
p \ll n
) and
p = n
. Easy-to-handle criteria are presented for checking the validity of the simplifications when using these expressions for evaluating the recombination velocities from experimental data.