Study of the free carrier characteristics and surface morphology of AlGaAs/GaAs thin films deposited using MOCVD

IF 2.8 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Optical Materials Express Pub Date : 2024-02-07 DOI:10.1364/ome.515432

Wei Liu, Xiaochuan Ji, Jianglin Dai, Jinlong Zhang, Hongfei Jiao, Xinbin Cheng, and Zhanshan Wang

{"title":"Study of the free carrier characteristics and surface morphology of AlGaAs/GaAs thin films deposited using MOCVD","authors":"Wei Liu, Xiaochuan Ji, Jianglin Dai, Jinlong Zhang, Hongfei Jiao, Xinbin Cheng, and Zhanshan Wang","doi":"10.1364/ome.515432","DOIUrl":null,"url":null,"abstract":"Ultra-low loss optical thin films find broad applications in fields such as vertical-cavity surface-emitting lasers and optical atomic clocks. The main optical losses in AlGaAs/GaAs distributed Bragg reflectors (DBRs) prepared using metal-organic chemical vapor deposition (MOCVD) arise from absorption loss caused by free carriers within the layers and scattering loss caused by surface roughness. In this study, we fabricated AlGaAs and GaAs single-layer thin films with varying Al compositions on substrates of three crystal orientations and under different V/III ratios. The dependence of carrier concentration and surface morphology on different substrates and growth conditions was investigated. Thin films grown on substrates with three different crystal orientations exhibited three distinct growth modes (step-flow mode, SK mode, and FM mode). The impact of the V/III ratio on the growth mode was found to be complex. Higher V/III ratios resulted in poorer morphology for films grown on (100) substrates, while better morphology was observed on (211) B substrates. Furthermore, the surface morphology of films grown on (100) 15° off substrates showed less sensitivity to changes in the V/III ratio. With increasing Al composition, the carrier concentration of the films significantly increased. Elevating the V/III ratio proved effective in suppressing the incorporation of carbon, thereby reducing the carrier concentration of AlGaAs films. GaAs films exhibited a low carrier concentration at an appropriate V/III ratio. Additionally, the distinct abilities of different substrates to adsorb impurities exerted a significant impact on the carrier concentration of the films. This study demonstrates that, under optimal conditions, it is feasible to fabricate AlGaAs/GaAs Bragg mirrors with low carrier concentration and relatively small roughness on (100) 15° off substrates.","PeriodicalId":19548,"journal":{"name":"Optical Materials Express","volume":"217 1","pages":""},"PeriodicalIF":2.8000,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Optical Materials Express","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1364/ome.515432","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}

引用次数: 0

Abstract

Ultra-low loss optical thin films find broad applications in fields such as vertical-cavity surface-emitting lasers and optical atomic clocks. The main optical losses in AlGaAs/GaAs distributed Bragg reflectors (DBRs) prepared using metal-organic chemical vapor deposition (MOCVD) arise from absorption loss caused by free carriers within the layers and scattering loss caused by surface roughness. In this study, we fabricated AlGaAs and GaAs single-layer thin films with varying Al compositions on substrates of three crystal orientations and under different V/III ratios. The dependence of carrier concentration and surface morphology on different substrates and growth conditions was investigated. Thin films grown on substrates with three different crystal orientations exhibited three distinct growth modes (step-flow mode, SK mode, and FM mode). The impact of the V/III ratio on the growth mode was found to be complex. Higher V/III ratios resulted in poorer morphology for films grown on (100) substrates, while better morphology was observed on (211) B substrates. Furthermore, the surface morphology of films grown on (100) 15° off substrates showed less sensitivity to changes in the V/III ratio. With increasing Al composition, the carrier concentration of the films significantly increased. Elevating the V/III ratio proved effective in suppressing the incorporation of carbon, thereby reducing the carrier concentration of AlGaAs films. GaAs films exhibited a low carrier concentration at an appropriate V/III ratio. Additionally, the distinct abilities of different substrates to adsorb impurities exerted a significant impact on the carrier concentration of the films. This study demonstrates that, under optimal conditions, it is feasible to fabricate AlGaAs/GaAs Bragg mirrors with low carrier concentration and relatively small roughness on (100) 15° off substrates.

查看原文本刊更多论文

利用 MOCVD 沉积的 AlGaAs/GaAs 薄膜的自由载流子特性和表面形貌研究

超低损耗光学薄膜在垂直腔面发射激光器和光学原子钟等领域有着广泛的应用。使用金属有机化学气相沉积（MOCVD）技术制备的 AlGaAs/GaAs 分布布拉格反射器（DBR）的主要光学损耗来自层内自由载流子造成的吸收损耗和表面粗糙度造成的散射损耗。在这项研究中，我们在三种晶体取向和不同 V/III 比率的基底上制备了不同铝成分的 AlGaAs 和 GaAs 单层薄膜。研究了载流子浓度和表面形貌对不同衬底和生长条件的依赖性。在三种不同晶体取向基底上生长的薄膜呈现出三种不同的生长模式（阶梯流模式、SK 模式和调频模式）。研究发现，V/III 比率对生长模式的影响是复杂的。V/III 比率越高，在 (100) 基底上生长的薄膜形态越差，而在 (211) B 基底上生长的薄膜形态越好。此外，在偏离 (100) 15° 的基底上生长的薄膜的表面形态对 V/III 比率变化的敏感性较低。随着铝成分的增加，薄膜的载流子浓度显著增加。事实证明，提高 V/III 比率可以有效抑制碳的加入，从而降低 AlGaAs 薄膜的载流子浓度。在适当的 V/III 比率下，砷化镓薄膜的载流子浓度较低。此外，不同基底吸附杂质的能力也对薄膜的载流子浓度产生了重大影响。这项研究表明，在最佳条件下，在 (100) 15° off 基底上制造载流子浓度低、粗糙度相对较小的 AlGaAs/GaAs 布拉格反射镜是可行的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Optical Materials Express MATERIALS SCIENCE, MULTIDISCIPLINARY-OPTICS

CiteScore

5.50

自引率

3.60%

发文量

377

审稿时长

1.5 months

期刊介绍： The Optical Society (OSA) publishes high-quality, peer-reviewed articles in its portfolio of journals, which serve the full breadth of the optics and photonics community. Optical Materials Express (OMEx), OSA''s open-access, rapid-review journal, primarily emphasizes advances in both conventional and novel optical materials, their properties, theory and modeling, synthesis and fabrication approaches for optics and photonics; how such materials contribute to novel optical behavior; and how they enable new or improved optical devices. The journal covers a full range of topics, including, but not limited to: Artificially engineered optical structures Biomaterials Optical detector materials Optical storage media Materials for integrated optics Nonlinear optical materials Laser materials Metamaterials Nanomaterials Organics and polymers Soft materials IR materials Materials for fiber optics Hybrid technologies Materials for quantum photonics Optical Materials Express considers original research articles, feature issue contributions, invited reviews, and comments on published articles. The Journal also publishes occasional short, timely opinion articles from experts and thought-leaders in the field on current or emerging topic areas that are generating significant interest.