Selective liquid phase epitaxy of GaAlAs/GaAs andots applications ro integrated optoelectronic devices

Abstract

Motivated by the necessities of selective processing techniques in integrated optoelectronics, selective liquid phase epitaxy of GaAlAs/GaAs material system has been studied and its applications to the integrated optoelectronic devices have been pursued. By the enhanced lateral diffusion into the window regions from the surrounding masked area, surface kinetics limited growth is predominant in the low-index crystallographic planes while the diffusion-limited growth is still dominant for the high-index planes and the large area windows. From the morphology analysis by the newly proposed modified Wulff``s construction it is shown that the growth forms evolve from the initial forms, which are determined by the corresponding window shapes, to the limiting forms which are determined by the growth rate anisotropy of the material irrespective of the window shapes. Before the growth forms reach to the limiting forms, they are determined by both the window shapes and the growth rate anisotropy. Therefore the transient growth forms can be controlled by the window shapes. The concept is very useful for device applications. For the device applications, some process and design considerations are presented based on the experimental and theoretical results of the growth kinetics, growth forms and some process details. Both diffusion-limited growth and surface kinetics limited growth have proved to be useful for the device applications. As such examples, integrated optical taper structure have been fabricated using the thickness controllabilities of the diffusion-limited growth while 45 degree mirror bent-waveguide structures using as-grown facets take advantages of the facet growths in the surface kinetics limited growth. Using the bent-waveguide structures, new integrated diode lasers are proposed and their static operation characteristics have been analyzed using the scattering matrix and the rate equation formulations. It is theoretically predicated that the bent-waveguide...