Diffusion Length Of Species Research Articles

Growth kinetics and mass transport mechanisms of GaN columns by selective area metal organic vapor phase epitaxy

Three-dimensional GaN columns recently have attracted a lot of attention as the potential basis for core-shell light emitting diodes for future solid state lighting. In this study, the fundamental insights into growth kinetics and mass transport mechanisms of N-polar GaN columns during selective area metal organic vapor phase epitaxy on patterned SiOx/sapphire templates are systematically investigated using various pitch of apertures, growth time, and silane flow. Species impingement fluxes on the top surface of columns Jtop and on their sidewall Jsw, as well as, the diffusion flux from the substrate Jsub contribute to the growth of the GaN columns. The vertical and lateral growth rates devoted by Jtop, Jsw and Jsub are estimated quantitatively. The diffusion length of species on the SiOx mask surface λsub as well as on the sidewall surfaces of the 3D columns λsw are determined. The influences of silane on the growth kinetics are discussed. A growth model is developed for this selective area metal organic vapor phase epitaxy processing.

Selective-area MOVPE growth for 10 Gbit/s electroabsorption modulator integrated with a tunable DBR laser

We have designed and fabricated electroabsorption modulator integrated monolithically with a distributed Bragg reflector laser using selective area growth (SAG) by metalorganic vapor phase epitaxy (MOVPE). Through the bandgap engineering due to the growth rate enhancement and compositional variation from the difference of migration and/or diffusion length of species by various SAG mask pattern, we have achieved the photoluminescence peak wavelengths of active layer in the laser, modulator, and Bragg grating regions to 1.557, 1.503, and 1.442 μm, respectively. The electroabsorption modulator-integrated laser shows a good performance including threshold current of below 6 mA, output power of 5 mW for 45 mA current injected in the active region, and high side-mode suppression ratio over 45 dB with the 3-dB modulation bandwidth over 11 GHz.