Investigations on oxide-free InGaAlAs waveguides grown by narrow stripe selective MOVPE

Oxide-free InGaAlAs waveguides have been grown on the InP substrates patterned with pairs of SiO₂ mask stripes using narrow stripe selective MOVPE. The mask stripe width is varied from 0 to 40 mum, while the window region width between a pair of mask stripes is fixed at 1.5, 2.5 and 3.5 mum, respectively. Smooth surfaces and flat interfaces are obtained in the selectively grown InGaAlAs waveguides. There exhibit strong dependences of the thickness enhancement ratio and the photoluminescence (PL) spectrum on the mask stripe width and the window region width for the InGaAlAs waveguides. A large PL peak wavelength shift of 79 nm and a PL full width of at half maximum (FWHM) of less than 64 meV are obtained simultaneously. Some possible interpretations for our investigations are presented by considering both the migration effect from a masked region (MMR) and the lateral vapor diffusion effect (LVD)