  Quarter-wave OLEDS are microcavity devices that can operate in the low
finesse limit and achieve high efficiency (> 300 lm/W) by using interference to
reduce the onset current for the transition to stimulated emission. In this
work we study the transition to stimulated emission and compare the kinetics
and electrical properties of conventional and quarter-wave devices. We show
that suppression of spontaneous emission into the vertical mode can result in a
sharp transition to stimulated emission at (\gamma /eV)I ~ N_se/\tau_sp where
N_se/\tau_sp is determined by optical parameters, and we find a previously
observed electrical signature for the transition where the excited state
population becomes fixed at low current density. We then study the role of loss
mechanisms in the quarter-wave configuration and conclude with some
requirements for practical device.
