Fundamental Properties of GaAsN and InGaAsN - Toward Optoelectronic Applications

提出了在GaAs衬底上生长和表征传统iii - v化合物（如GaAs， InAs）与III-N化合物（如GaN， InN）的三元合金。这些合金有望具有立方锌闪锌矿结构，并具有直接带隙。然而，砷化镓和氮化镓之间的大晶格不匹配以及砷化镓和氮化镓之间原子轨道能量的差异导致了带隙的成分依赖性非常不寻常。在gaas1 - xnxx中的光学弯曲系数至少比在普通iii -谷中遇到的要大一个数量级。其带隙随N分数的增加而迅速减小。这提供了在1.3 - 1.55mm范围内工作的GaAs衬底上制备新型光电器件的可能性。本研究所需的材料将通过金属有机分子束外延（MOMBE）生长。氮掺入对外延层的物理微观结构和光学带隙的影响将通过各种实验技术来确定。拉曼散射将用于研究微观结构效应，如氮掺入、自发有序和相分离。拉曼结果将使用键极化率、双组分分子模型、有限尺寸和应变效应来建模。近带边缘光学特性将通过连续波和时间分辨光致发光进行广泛的研究。这些将集中于氮的掺入如何改变载流子的重组。椭圆偏振法和反射率法将用于获取带隙以上光学特性的信息。现象变形势模型将用于解释InGaAsN/GaAs的量子阱和超晶格中的应变效应。最后，基于InGaAsN/GaAs的量子阱结构将用作有源层，用于制作波长范围为1.3-1.55 mm的垂直腔激光器。

It is proposed to grow and characterize ternary alloys of conventional III-Vcompounds (e.g. GaAs, InAs) with III-N compounds (e.g. GaN, InN) on GaAssubstrates. These alloys are expected to be cubic with the zincblende structure and topossess a direct bandgap. However, the large lattice mismatch between GaAs and GaNand the difference in atomic orbital energies between As and N result in a very unusualcompositional dependence of the bandgap. The optical bowing coefficients in GaAs1-xNxare at least an order of magnitude greater than those encountered in common III-Valloys. Its bandgap decreases rapidly with increasing N fraction. This offers a possibilityof preparing novel optoelectronic devices, on GaAs substrates, operating in the 1.3 - 1.55mm range. The materials needed for this study will be grown by Metalorganic MolecularBeam Epitaxy (MOMBE). The effect of nitrogen incorporation on physicalmicrostructure and optical bandgap of epitaxial layers will be determined by a variety ofexperimental techniques. Raman scattering will be used to investigate microstructuraleffects such as nitrogen incorporation, spontaneous ordering, and phase separation.Raman results will be modeled using bond polarizability, a two-component molecularmodel, finite size, and strain effects. Near band edge optical properties will be studiedextensively by cw and time-resolved photoluminescence. These will focus on hownitrogen incorporation modifies carrier recombination. Ellipsometry and reflectancemethods will be used to gain information of the above-bandgap optical properties.Phenomenological deformation potentials model will be used to account for strain effectsin quantum wells and superlattices of InGaAsN/GaAs. Finally, quantum well structuresbased on InGaAsN/GaAs will be used as active layers to make vertical cavity lasersoperating in the wavelength range of 1.3-1.55 mm.