Distributed Bragg reflectors (DBRs) can be fabricated by electrochemically etching nitride epitaxial structures consisting of alternating layers of highly n-type doped and non-intentionally doped (NID) GaN. Threading dislocations (TDs) can be electrochemically etched into transport pipelines that can carry the etchant through the NID layers to access the doped material. Experimentally this has been shown to involve a mechanism where the etching pathway may follow one TD into a doped layer and then propagate sideways through the doped layer to continue via a different TD. Across multiple layers this process creates complex pore structures that have been described as 'cascades'. Here, we build a stochastic simulation for the DBR etching process that can reproduce some key features of the observed microstructures including the cascade morphology. By comparing the simulation output to samples etched at a range of voltages, we show that we can reproduce variations in experimental chronoamperometry data with applied bias by varying the probability of etching the doped layers within the simulation. The outputs of the resulting simulations replicate the experimentally observed cascade morphology. At higher voltages, experimental data reveal a lower proportion of cascade features, a trend that is also replicated by the simulations for relevant probability values. Outputs of the simulations also correlate well with experimental chronoamperometry data for samples where - unlike in a DBR - the thicknesses of the doped layers vary through the epitaxial multilayer, suggesting that the probabilistic simulation can be applied to a range of structures to help understand the dislocation-mediated electrochemical etching process.
Monolithic integration of 940 nm AlGaAs distributed Bragg reflectors on bulk Ge substrates
高质量940 nm Al $_x$ Ga $_{1-x}$ As n型分布式布拉格反射器（DBR）成功地在非切割Ge（100）衬底上单片生长。Ge-DBR的反射率光谱与传统GaAs衬底上生长的反射率光谱相当，并且具有光滑的形貌、合理的周期性和均匀性。这些结果强烈支持VCSEL的生长和制造上更可扩展的体Ge衬底的大规模生产的AlGaAs基VCSEL。
Enhanced spectral range of strain-induced tuning of quantum dots in circular Bragg grating cavities
Julius-Maximilians-Universität Würzburg（维尔茨堡大学）；Würzburg-Dresden Cluster of Excellence ct.qmat（维尔茨堡-德累斯顿卓越集群 ct.qmat）；University of Freiburg（弗莱堡大学）；Centre for Nanosciences and Nanotechnologies CNRS, Universite Paris-Saclay（巴黎萨克雷大学法国国家科学研究中心纳米科学与技术中心）；Karlsruhe Institute of Technology (KIT)（卡尔斯鲁厄理工学院）
