Advanced GaAs Based Laser Fabrication (Feasibility Study)

GaAs材料的研究已经将器件的工作波长扩展到电信和医疗诊断应用中，并且与现有的基于InP的器件相比，提供了许多优势。这些都围绕着使用更大的基板来降低成本，以及通过改进载流子限制来实现更高温度（或非冷却）操作的更大频带偏移。然而，基于GaAs的器件制造相当不成熟，GaAs激光器通常只能作为Fabry-Perot脊结构，具有高度不对称输出，表面复合和宽发射光谱。分布式反馈（用于单模操作）和埋藏异质结构激光器（对称输出，减少表面损耗）等技术在商用InP器件中很常见。本提案中基于GaAs的埋藏异质结构器件的发展依赖于一种新的方法来避免暴露的AlGaAs的有害再生，从而允许GaAs基材料的埋藏异质结构技术。基于砷化镓的埋藏异质结构激光器将在电学和光学性能方面进行开发和评估，特别是使用远场分析技术进行光发射的空间分布。固体源和气体外延过度生长方法将在各种条件下进行评估和比较。埋地光栅（分布反馈）将被开发，最初用于单模脊激光器，然后最终纳入埋地异质结构分布反馈激光器。

GaAs materials research has extended the operating wavelengths of devices to those used in telecommunications and medical diagnostic applications, and offers a number of advantages over incumbent InP based devices. These revolve around the use of larger substrates leading to cost reductions, and greater band offsets allowing higher temperature (or uncooled) operation of a device through improved carrier confinement. However, GaAs based device fabrication is rather immature, with GaAs lasers typically only available as Fabry-Perot ridge structures, which exhibit highly asymmetric output, surface recombination, and broad emission spectra. Technologies such as distributed feedback (for single mode operation) and buried heterostructure lasers (symmetric output, reduced surface losses) are commonplace in commercial InP devices. The development of GaAs based buried heterostructure devices in this proposal relies upon a novel approach in circumventing deleterious regrowth upon exposed AlGaAs, allowing buried heterostructure technology for GaAs based materials. GaAs based buried heterostructure lasers will be developed and assessed in terms of electrical and optical performance, in particular the spatial profile of the optical emission using far field analysis techniques. Solid source and gaseous epitaxial overgrowth methods will be assesed and compared under various conditions. Buried gratings (distributed feedback) will be developed, initially for use in a single mode ridge laser, before ultimately incorporation in a buried heterostructure distributed feedback laser.