Theoretical And Experimental Investigations On Novel Ⅲ-Ⅴ Optoelectronic Materials

The research work of this dissertation was mainly supported by the National Basic Research Program of China "Basic Research on Integrated Optoelectronic Devices and Microstructure Optical Fibers with Structure and Technology Innovations for Future Advanced Optical Communications" (No.2003CB314900), which Professor Ren Xiaomin is responsible for as a chief scientist. Additionally, part of the research work was also supported by the National High Technology R&D Program of China "Innovative Research on NovelⅢ-ⅤBoron-incorporated Optoelectronic Materials System for Monolithic Integration" (No. 2009AA03Z417).The development of the new generation of optical communication system will be based on new communication optoelectronic devices. And the major outstanding issues, which have been encountered during the investigation of integrated optoelectronic devices, are the compatibilities between different materials, different structures and different processes, in which the compatibilities between different materials have an important influence on enhancing the performances of optoelectronic devices. The thesis was mainly focused on theⅢ-Ⅴoptoelectronic materials. GaAsN and GaNP optoelectronic materials which constitute GaNAsP were calculated. The growth and measurement of the B-incorporated optoelectronic material have also been carried out. Research results are as listed below.1. By the CASTEP software which is based on density-functional theory (DFT), the lattice constant and energy bandgap of zinc-blende GaN, GaP and GaAs were calculated and analyzed.2. Based on the theoretical calculation of the above-mentioned binary alloys, the SQS-8 super-cell model of Ga8As8-xNx alloys was set up. The energy bandgap structures of GaAsN alloys with different N content were calculated by the cluster expansion approximation. Simulated results show that the bandgap bowing parameter of GaAsN alloy depends on the N content. When the N content is 12.5%,25%, the correspondingΓ1c-Γ15v transition bowing parameter is 8.29eV,5.90eV, respectively. And when the N content is increased to 25% (P-4M2,P-43M),50% and 62.5%, the energy bandgap will be closed.3. The SQS-4 super-cell model of Ga4NxP4-x alloy was also set up, and the energy bandgap structures of GaN0.25P0.75 were calculated. The calculation results show that the energy bandgap of GaN0.25P0.75 is indirect and the corresponding X1c-Γ15v transition bowing parameter is 8.91eV. With the further increase of N content to 50% and 75%, the bandgap will be closed.4,A series of BAlAs samples with boron(B) composition ranging from 0.4% to 4.4% have been grown on (100)GaAs substrates by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). The experimental results show that 580℃is the optimum temperature for BAlAs growth. At 580℃, boron incorporation ratio will increases with the increment of gas phase triethylboron (TEB) mole fraction. Meanwhile, the full width at half maximum (FWHM) value of BAlAs diffraction peak and the surface root. mean square (RMS) roughness measured by AFM also increased (FWHM value of 204.7arcsec and RMS roughness of 29.086nm were achieved at B composition of 4.4%), which demonstrated the crystallinity deterioration of BAlAs materials.5,BGaAs with B composition ranging from 1.2% to 5.8% and corresponding lattice-matched BGaInAs samples have been grown on (100)GaAs substrates by LP-MOCVD.