Applying First-principle Calculation In Optimizing The Epitaxy Of Different-dimensional ?-? Compounds

Direct-bandgap ?-? compounds semiconductors,like III-nitrides and III-arsenide,have shown great potential in application of illumination,communication and energy due to its excellent chemical stability,photoelectronic properties and electronic properties.Furthermore,developed fabrication and epitaxy technology makes low-dimensional materials come true.Nowadays,application of different-dimensional ?-? semiconductors is limited by the quality of materials.Further development of materials quality needs more breakthroughs in fabrication capacity and mechanism of epitaxial growth.In this dissertation,Epitaxial growth of different-dimensional ?-? semiconductors materials,including revelant mechanism,are deeply researched through regulating the parameters,inproving methods of epitaxy and building a model about adsorption,migration and accumulation of adatoms in growth based on density functional theory.Achievements of my research can be defined into three parts below:?1?Apply pulsed laser deposition?PLD?system to avoid the interface rotation of La_0.3Sr_1.7Al Ta O₆?111?/Ga N?0002?and achieve extremely high-quality Ga N films with a FWHM of 0.06°in the peak of X-ray rocking curve.Research the adsorption of Ga/N adatoms on LSAT?111?surface and interface adhesion of LSAT/Ga N based on density-functional theory.Unriddle the mechanism of interface rotation and avoiding interface rotation by PLD.?2?Apply moleculat beam epitaxy?MBE?system to achieve the controllable growth of InGaN nanorods?NRs?through regulating In/Ga flux ratio and solve the problem of coalesce of InGaN NRs.Based on density functional theory,research the adsorption behavior of In adatoms on the top and the wall of NRs,find out the mechanism of controlling the radium and height of NRs by regulating In/Ga ratio.Develop the method of researching adatoms adsorption into researching“start-to-end”adatoms migration.?3?Induce the mis-cutting angle of Ga As?100?A substrates in growing self-assembled InAs quantum dots?QDs?in MBE and achieve InAsQDs matrix with highly uniform sizes. Based on the mechanism of growing QDs in SK mode and density functional theory, unriddle the relationship between cutting-angles of substrates and migration of In adatoms. Develop the method of researching“start-to-end”adatoms migration into researching continuous migration of adatoms on rough surface.