Abstract:
In this work, a wurtzite-strained nitride based single quantum well laser structure has been
designed using a 12Å InN well layer and 15Å In0.25Ga0.75N barrier layer which is characterized
and optimized for an optical output of 1330nm wavelength known for short distance
communication. A Separate Confinement Heterostructure (SCH) layer of GaN has been used for
providing better confinement for carrier and photon. Materials and device parameters are selected
using practical considerations for fabrication process. A self-consistent Schrodinger Solver along
with a simulation model for obtaining optical properties has been developed for the
characterization which is verified with previously published work. In self-consistent Schrodinger
solver, two Schrodinger equations for both conduction and valence band have been solved
followed by the performance of Poisson’s equation. The 6-band k.p formalism has been utilized
for valence band calculation including valence band mixing, strain effect, spontaneous
polarization, and piezoelectric polarization effect, etc. With the performed energy subbands,
interband transition momentum matrix elements are calculated. Several optical characteristics like
spontaneous emission rate, material gain, radiative recombination current density etc. are
performed from the obtained electronic properties. Also parameters like, peak material gain versus
carrier density and material gain versus radiative recombination current density are found out to
characterize the structure. At carrier density of 6×1019 cm-3 and T = 300K, the peak optical gain of
5261.5187 cm-1 has been found at emission wavelength of 1336.7 nm. The peak spontaneous
emission rate per energy interval per volume is 7.21×1027 s-1cm-3eV-1 at 1329.55 nm wavelength.
Later, a genetic algorithm based optimization process has been performed to obtain the maximum
spontaneous emission rate and maximum optical gain for the structure taking well width, barrier
width, injection carrier density and SCH width are taken as variables into consideration. From the
characterization, it has been found that the device will provide good amplification for TEpolarization
light. This structure shows a good amount of spontaneous emission rate for lasing
action with respect to the other structures published previously. Moreover, it shows a good
improvement of material gain which will provide better LED and LASER action. A higher
differential gain has been found for this structure which will provide higher modulation bandwidth
and lower frequency chirp. Besides, the structure shows good amount of optical gain with respect
to recombination current density. All these performances make this structure promising for
LASER application at around 1330nm emission wavelength.
