Research On Light Guiding Properties Of GAAS Semiconductor Nanowires

The research work of this master’s thesis is mainly supported by grants from the National Basic Research Program of China (No.2010CB327601), the PH. D Programs Foundation of Ministry of Education of China (No.20120005110011), the NationalNatural Science Foundation of China (No.61020106007), New CenturyExcellent Talents in University (No. NCET-08-0736), and the111Programof China (B07005).In resent years, semiconductor nanowires have gained significant attention in the nano photoelectronics community for their unique electrical and optical properties. In particular, single semiconductor nanowires can function as waveguides and Fabry-Perot resonant cavities, which have a wide prospective of the next generation of nanolaser applications. Research of the modal properties of the nanowires is attached important significance for designing and engineering the nanowire lasers. In this paper, the theoretical work about modal properties of single gallium arsenide nanowires and GaAs/InGaAs/GaAs nanowire core-mutishell heterostructures is carried out. The main research work and achievements are listed as follows:1. Semiconductor nanowires are introduced with its synthetic control method and its applications on photonic and electronic devices. In the next, we describe the development and research of semiconductor nanowire lasers. Semiconductor nanowires can not only serve as gain medium, but also resonant cavities. Different nanowire structures with different materialcan be frabricated lasers with different wavelengths.2. Adopting the frequency-difference time-domain (FDTD) method, we have thereotically analyzed the single GaAs nanowire with its mode distribution, threshold gain and resonant properties. The results show the following conculsions.①GaAs nanowires can support multiple modes including HE11、TE01and TM01, and the modes appear one after another with increasing radius of the nanowire.②The threshold gain of the GaAs nanowire is a function of the length, facet reflection and confinement of the nanowire. When the radius of the nanowire is larger than110nm and smaller than180nm, the TE01mode has the lowest threshold gain and TM01has the lowest if the radius if lager than180nm.③A single GaAs nanowire can be used as a resonant cavity. With increasing the length and radius of the nanowire, the Q values of the modes HE11、 TE01and TM01increase, and at large size of the nanowire, the Q value of TE01is much larger than that of HE11and TM01.3. Using FDTD, the theoretical research on modal properties of GaAs/InGaAs/GaAs nanowirecore-mutishell heterostructures is launched. And this work is concluded that in this structure, InGaAs layer is supposed to be the gain medium and the inner GaAs serves as a resonant cavity. And the field distribution of this structure is very similar with that of single GaAs nanowires. The larger the inner GaAs nanowire or the thicker InGaAs layer is, the more modes the nanowire heterosturctures can support. There exist the critical dimensions of the nanowire heterostructureswhere only one single mode is supported in the nanowire, which is HE11mode. When In composition in InGaAs reaches a specific value, only HE11mode is supported in the GaAs/InGaAs/GaAs nanowirecore-mutishell heterostructures, while the other modes are cutoff.