The current-voltage relations for the barrier regions in the SCH quant
um well laser diode are derived in general terms under the assumption
of charge neutrality. The boundary conditions are established at the q
uantum well SCH region interface by the clamping of the Fermi levels i
n the quantum well above threshold, It is shown that the current flow
is comprised of opposing drift and diffusion hows with drift slightly
in excess of diffusion, The recombination current in the SCH region ha
s contributions from both drift and diffusion mechanisms, Expressions
are also derived to determine the resistance and capacitance associate
d with the SCH transport. The appropriate small-signal current versus
small-signal Fermi level dependence is specified for application to th
e small-signal laser response formulation.