Studies of High Quality GaAs Layers Heteroepitaxially Grown on Si Substrates by Microchannel Epitaxy and Fabrication of Laser Diodes

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Growth of III-V materials on Si substrates is a key technology for fabricating opto-electronic integrated circuits (OEICs). Though a lot of studies about the growth of III-V materials on Si have been carried out, a large lattice mismatch and a big difference in the thermal expansion coefficient between Ill-V materials and Si substrates still bring high dislocation density (〜10ィイD16ィエD1 cmィイD1-2ィエD1) and strong residual stress in the layers. The dislocations in the Ill-V materials strongly deteriorate the device characteristics and their lives especially in optical devices, therefore, further crystallinity improvement is necessary to obtain optical devices with high performance and commercial reliability.Microchannel epitaxy (MCE) is a new technology to grow thin layers laterally through an opening in SiOィイD22ィエD2 film, which is called as "microchannel". In MCE, epitaxial relationship is transferred through a microchannel to the grown layer but the defects such as dislocations are not continued except a narrow microchannel. Therefore, MCE has a very-high potentiality for overcoming the above-mentioned difficulties in heteroepitaxy.MCE was applied to the growth of dislocation-free GaAs layers on Si substrates. By optimizing the growth conditions for maximizing the ratio of the width of a MCE layer to the thickness (W/T ratio), very wide dislocation-free regions, which were as large as 100 μm, were consequently obtained, Spatially resolved photoluminescence measurements showed that the optical quality of the MCE layers was almost the same as that of a homoepitaxially grown ones. The vertical cavity surface-emitting laser was tried to fabricate on the MCE layer. As the result, an excellent optical quality of the laser, which shows a simulated emission on the light output by current injection, was achieved. An optimization of the fabrication process of the lasers will bring to the realization of an elemental OEIC.