Five-dimensional alloy growth of AlInGaNAs and fundamental investigation for realizing Opto-Electronic Integurated Circuits

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Since last year, we have started fundamental investigation of 2-,3- and 4-dimensional alloy film growth on Si substrates using nitride semiconductors including In such as InN/Si, InNAs/Si, InGaNAs/Si as a preliminary research for obtaining 5-dimensional alloy growth of AlGaInAsN/Si with high film quality, and clarified some problems on crystal growth. As a result, it is fundamentally impossible to grow nitride semiconductors including In at high temperatures and the film quality abruptly degraded with an increase of In concentration. Furthermore, it was found that InN has a band-gap energy (0.7 eV) narrower than the value (1.9 eV) have been generally believed for long time. It is necessary to take the effect of the revised band-gap energy of InN into consideration for researching 5-dimensional alloy growth of nitride semiconductors including In. This year, we have investigated the cause of change into narrow band-gap energy for alloy growth of nitride semiconductors including In and in … More vestigated the possibility of new material using' nitride semiconductors for realization of optical electrical integrated circuits (OEIC) in the future. Furthermore, we tried to grow the InN and GaN films on GaAs besides Si as a substrate for OEIC and investigated the optimum growth conditions. It is usually known that hexagonal-GaN and -InN crystals were obtained on cubic-Si and -GaAs substrates. However, when being grown directly at low temperatures such as 500-600 oC, we found that single cubic-GaN and -InN with high film quality could be grown on these substrates with the same crystal structure. It indicates the high possibility of realization of OEIC in the future. From annealing experiments of InN films, we found that it was possible to control oxygen concentration in the film by applying the substrate voltage during growth and, as a result, we succeed in controlling the band-gap energy of InN. The cause is not always the formation of In2O3 crystal grains with wide band-gap energy in the film although the effect of oxygen impurities in the film must be considered. We submit the positive influence of oxygen in the 5-dimensional alloy growth of nitride semiconductors for realization of OEIC. Less