Reproducible growth of narrow linewidth multiple quantum well graded index separate confinement distributed feedback (MQW-GRIN-SCH-DFB) lasers by MOVPE

Overgrowth of submicron-patterned surfaces for buried index contrast devices

“…For much smaller corrugations, with a period of the order of a few hundred nanometres, Nagai et al observed that the bulk of the amplitude degradation occurs within the first 15 minutes of exposure to elevated temperatures [28]; thus, the amount of profile alteration is significantly less controllable during the initial heating stages and can lead to significant profile deviations in submicron-patterned gratings. In an effort to counteract the rapid profile alteration and amplitude degradation, yet simultaneously preserve a 'smoothed' sawtooth profile, InP and InGaAsP corrugated surfaces are typically exposed to an As/P ambient during the thermal desorption of the oxide [29][30][31][32][33][34]. The near absence of As desorption compared to P desorption at InP growth temperatures effectively reduces the mobility of the adatoms, thereby decreasing alteration of the corrugated surface profile.…”

“…The near absence of As desorption compared to P desorption at InP growth temperatures effectively reduces the mobility of the adatoms, thereby decreasing alteration of the corrugated surface profile. Although the profile degradation is reduced, it is not completely stifled during the thermal oxide desorption process; gratings typically experience more than 10% amplitude reduction [29,34,35]. The addition of As during thermal cleaning of an InP surface creates an InAsP layer, with the magnitude of As/P exchange not only dependent on the As/P ratio, but also dependent on the exposed crystallographic planes [36].…”

New DFB grating structure using dopant-induced refractive index step

“…A Bragg grating buried inside the laser cavity provides the single wavelength operation. The early structures used a single growth process [1]; V-grooves were etched on the surface of an InP wafer followed by overgrowth of a thin layer of InGaAsP at the bottom of the Vgrooves and then filled with InP. This single growth structure had several shortcomings that affected device reliability, due to the difficulty in controlling the complex gratings overgrowth over the crystal facets [2,3], maintaining the compositional homogeneity of the InGaAsP layer and possible presence of crystal defects at the growth interface [3].…”

Recent advances in metal-organic vapor phase epitaxy

“…Growth on patterned substrates has focused on the formation of distributed Bragg reflector structures [91] and the growth of quantum lines [92]. The formation of Bragg reflectors is typically accomplished by the patterning of an existing epitaxial structure through conventional photolithographic patterning of a holographic image.…”