First-Principles Calculation And Experimental Study On Boron-Incorporated Optoelectronic Materials

With the development of the Internet, the demand for the wider band resource is driving the development of the communication system. Optical fiber communication is developing towards new generation of optical networks, which would be intelligent, integrated, low cost and reliable. So the higher demand for optical device is needed. Optical device can be divided into integrated ones and separated ones. The integrated ones possess the advantages that the separated ones don't have, which are small size, small parasitic, low cost and highly reliable. 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.In order to solve the problem of the compatibilities between different materials, the exploration of new optoelectronic materials whose lattice constant matches GaAs or Si, and the bandgap locates in the 1.3-1.55μm wavelength range of optical communications, may be the perfect resort. People found that, GaInNAs(Sb), which has the same lattice constant with GaAs, is the only material, whose wavelength can meet the long wavelength demand of optical communications. So GaInNAs(Sb) is a candidate for InGaAsP/InP. Using First Principles Theory and Generalized Gradient Approximation (GGA), our research focused on the theory calculation of boron-incorporated optoelectronic materials BGaSb, by compared to the calculation result of GaAsN, which is the basic component of GaInNAs(Sb). Also I have taken part in the B-incorporated material samples's grown and test work. Research results are as listed below.1. Using the CASTEP software based on density-functional theory (DFT), the lattice constants and energy bandgap structures of GaAs, GaN, GaSb and BSb were calculated and analyzed.2. Based on the calculation of binary alloys, the SQS-8 super-cell model was set up, and the energy bandgap structures of GaAs_1-xN_x with different N content were calculated, with the cluster expansion approximation. Simulated results show that the bandgap bowing parameter depends on the N content, when the content is 0.125, 0.25, 0.75, 0.875, the corresponding bowing parameter isl4.5eV, 9.28eV(the bandgap is closed),10.4eV, 16.7eV.3. The BGaSb SQS-16 super-cell model was set up, and the energy bandgap structures of B_xGa_1-xSb with different B content were calculated. The calculation result shows that the energy bandgap has a little increase with the increse of B content. Based on the calculation result and Vegard's law, we found that when boron content is between 0 and 18.75%, the value ofΓ_1cΓ_15v band-gap energy is increasing monotonously by～17.5 meV/%B with a small band-gap bowing parameter (2.23 eV). When boron content x is below 10.08%, B_xGa_1-xSb is a direct band-gap alloy. And the formation enthalpy is increasing rapidly with the increasing of B content in BGaSb. The comparison between the formation enthalpies of BGaAs, InGaAs and BGaSb indicates that the content of boron in B_xGa_1-xSb may be able to reach 7%.4,The BAlAs, BGaInAs materials have been grown on the (001) GaAs substrate by LP-MOCVD. The samples were tested by DCXRD and SIMS. And we have grown ten periods of BGaAs/GaAs and BGaInAs/GaAs MQW, under the 580℃.