A. Ramaswamy et al., ELECTRICAL CHARACTERISTICS OF PROTON-IMPLANTED VERTICAL-CAVITY SURFACE-EMITTING LASERS, IEEE journal of quantum electronics, 34(11), 1998, pp. 2233-2240
The electrical characteristics of proton-implanted GaAs quantum-well v
ertical-cavity surface-emitting semiconductor lasers (VCSEL's) have be
en studied. We show that the 2kT current, observed over many decades i
n these VCSEL's, is primarily due to nonradiative recombination mechan
isms. These include surface recombination at the edges of the proton-i
mplanted region and bulk recombination at defects and heterojunction i
nterface traps. The contribution of these mechanisms to the total nonr
adiative current and the threshold current density has been calculated
. Lateral spontaneous emission measurements have been used to prove th
at the radiative current has a kT behavior in the subthreshold region.
Electrical derivative measurements have been used to identify leakage
current paths through the proton-implanted region in the low-bias reg
ions. In addition, electrical derivative measurements have been used t
o measure the variation of series resistance with current near the las
ing threshold. From a consideration of the various current paths in th
e VCSEL, a lumped circuit equivalent model for the VCSEL has been deve
loped.