In this work, a two-step metal organic chemical vapor deposition (MOCVD) method was applied for growing β-Ga₂O₃ film on c-plane sapphire. Optimized buffer layer growth temperature (T_B) was found at 700 °C and the β-Ga₂O₃ film with full width at half maximum (FWHM) of 0.66° was achieved. A metal?semiconductor?metal (MSM) solar-blind photodetector (PD) was fabricated based on the β-Ga₂O₃ film. Ultrahigh responsivity of 1422 A/W @ 254 nm and photo-to-dark current ratio (PDCR) of 10⁶ at 10 V bias were obtained. The detectivity of 2.5 × 10¹⁵ Jones proved that the photodetector has outstanding performance in detecting weak signals. Moreover, the photodetector exhibited superior wavelength selectivity with rejection ratio (R_{250 nm}/R_{400 nm}) of 10⁵. These results indicate that the two-step method is a promising approach for preparation of high-quality β-Ga₂O₃ films for high-performance solar-blind photodetectors.

Expanding the optical communication band is one of the most effective methods of overcoming the nonlinear Shannon capacity limit of single fiber. In this study, GeSn resonance cavity enhanced (RCE) photodetectors (PDs) with an active layer Sn component of 9%–10.8% were designed and fabricated on an SOI substrate. The GeSn RCE PDs present a responsivity of 0.49 A/W at 2 μm and a 3-dB bandwidth of approximately 40 GHz at 2 μm. Consequently, Si-based 2 μm band optical communication with a transmission rate of 50 Gbps was demonstrated by using a GeSn RCE detector. This work demonstrates the considerable potential of the Si-based 2 μm band photonics in future high-speed and high-capacity optical communication.

High-performance germanium (Ge) waveguide photodetectors are designed and fabricated utilizing the inductive-gain-peaking technique. With the appropriate integrated inductors, the 3-dB bandwidth of photodetectors is significantly improved owing to the inductive-gain-peaking effect without any compromises to the dark current and optical responsivity. Measured 3-dB bandwidth up to 75 GHz is realized and clear open eye diagrams at 64 Gbps are observed. In this work, the relationship between the frequency response and large signal transmission characteristics on the integrated inductors of Ge waveguide photodetectors is investigated, which indicates the high-speed performance of photodetectors using the inductive-gain-peaking technique.High-performance germanium (Ge) waveguide photodetectors are designed and fabricated utilizing the inductive-gain-peaking technique. With the appropriate integrated inductors, the 3-dB bandwidth of photodetectors is significantly improved owing to the inductive-gain-peaking effect without any compromises to the dark current and optical responsivity. Measured 3-dB bandwidth up to 75 GHz is realized and clear open eye diagrams at 64 Gbps are observed. In this work, the relationship between the frequency response and large signal transmission characteristics on the integrated inductors of Ge waveguide photodetectors is investigated, which indicates the high-speed performance of photodetectors using the inductive-gain-peaking technique.

气溶胶对全球生态系统、物质循环具有重要影响，研究气溶胶光学参量等基础数据反演的准确性意义重大。利用来自欧洲气溶胶研究激光雷达网的4个观测站点（波坦察、莱比锡、里尔、埃武拉）在两次集中观测任务中的数据，对使用不同大气模式的温度、压强数据在反演气溶胶光学参量（消光和后向散射系数）及气溶胶分类中所产生的影响进行研究。结果表明：选用不同的大气模式对气溶胶光学参量进行反演会导致计算结果出现偏差，其中对于Raman法获取气溶胶消光系数的影响较大，在355 nm和532 nm处的最大偏差均可达到~20%。大气气溶胶浓度也会对不同模式的气溶胶光学参量反演结果产生影响，并且随观测波长的不同而有所差异。此外，不同大气模式会使气溶胶激光雷达比以及Ångström指数等与气溶胶类型相关的参量反演结果产生偏差，并最终影响气溶胶的分类。文中研究结果对于揭示大气模式的选取在反演气溶胶光学参量中的重要性以及对于气溶胶分类乃至大气科学的相关研究都具有重要的参考价值。

Beta-gallium oxide (β-Ga₂O₃) thin films were deposited onc-plane (0001) sapphire substrates with different mis-cut angles along < 112ˉ0> by metal-organic chemical vapor deposition (MOCVD). The structural properties and surface morphology of as-grownβ-Ga₂O₃ thin films were investigated in detail. It was found that by using thin buffer layer and mis-cut substrate technology, the full width at half maximum (FWHM) of the ( 2ˉ01) diffraction peak of theβ-Ga₂O₃ film is decreased from 2° onc-plane (0001) Al₂O₃ substrate to 0.64° on an 8° off-angledc-plane (0001) Al₂O₃ substrate. The surface root-mean-square (RMS) roughness can also be improved greatly and the value is 1.27 nm for 8° off-angledc-plane (0001) Al₂O₃ substrate. Room temperature photoluminescence (PL) was observed, which was attributed to the self-trapped excitons formed by oxygen and gallium vacancies in the film. The ultraviolet–blue PL intensity related with oxygen and gallium vacancies is decreased with the increasing mis-cut angle, which is in agreement with the improved crystal quality measured by high resolution X-ray diffraction (HR-XRD). The present results provide a route for growing high qualityβ-Ga₂O₃ film on Al₂O₃ substrate.Beta-gallium oxide (β-Ga₂O₃) thin films were deposited onc-plane (0001) sapphire substrates with different mis-cut angles along < 112ˉ0> by metal-organic chemical vapor deposition (MOCVD). The structural properties and surface morphology of as-grownβ-Ga₂O₃ thin films were investigated in detail. It was found that by using thin buffer layer and mis-cut substrate technology, the full width at half maximum (FWHM) of the ( 2ˉ01) diffraction peak of theβ-Ga₂O₃ film is decreased from 2° onc-plane (0001) Al₂O₃ substrate to 0.64° on an 8° off-angledc-plane (0001) Al₂O₃ substrate. The surface root-mean-square (RMS) roughness can also be improved greatly and the value is 1.27 nm for 8° off-angledc-plane (0001) Al₂O₃ substrate. Room temperature photoluminescence (PL) was observed, which was attributed to the self-trapped excitons formed by oxygen and gallium vacancies in the film. The ultraviolet–blue PL intensity related with oxygen and gallium vacancies is decreased with the increasing mis-cut angle, which is in agreement with the improved crystal quality measured by high resolution X-ray diffraction (HR-XRD). The present results provide a route for growing high qualityβ-Ga₂O₃ film on Al₂O₃ substrate.

GeSn detectors have attracted a lot of attention for mid-infrared Si photonics, due to their compatibility with Si complementary metal oxide semiconductor technology. The GeSn bandgap can be affected by Sn composition and strain, which determines the working wavelength range of detectors. Applying the Sn content gradient GeSn layer structure, the strain of GeSn can be controlled from fully strained to completely relaxed. In this work, the strain evolution of GeSn alloys was investigated, and the effectiveness of gradually increasing Sn composition for the growth of high-Sn-content GeSn alloys was revealed. Relaxed GeSn thick films with Sn composition up to 16.3% were grown, and GeSn photodetectors were fabricated. At 77 K, the photodetectors showed a cutoff wavelength up to 4.2 μm and a peak responsivity of 0.35 A/W under 1 V at 2.53 μm. These results indicate that GeSn alloys grown on a Sn content gradient GeSn structure have promising application in mid-infrared detection.

红外探测技术在激光测距、成像、遥感、夜视等领域有重要应用，降低红外光电探测器的尺寸、重量、功耗和成本，以及提高探测器的性能是目前的研究重点。本文综述了红外探测器技术的发展历程、工作原理及研究现状并对其未来发展方向进行了展望。内容主要涵盖基于碲镉汞、Ⅱ类超晶格、量子阱、量子点、硅基锗锡等材料的光子型红外光电探测器及其阵列。红外系统成本降低最终取决于在常温条件下耗尽电流限探测器阵列像素密度是否与系统光学元件的背景极限和衍射极限性能匹配，选择HgCdTe、Ⅱ类超晶格和胶体量子点等材料可提高光子探测器室温性能。各种红外探测器在性能方面各具特色，在实际应用中互为补充。

硅基IV族锗锡和锗铅合金材料带隙随组分可调，并可转变成直接带隙半导体材料，是研制硅基红外探测和发光器件的理想材料。本文首先介绍锗锡和锗铅材料外延生长工作，然后对锗锡光电器件的研究进展进行回顾和讨论。其中，随着锗锡合金中锡组分增加，锗锡光电探测器往高响应度和长探测截止波长方向发展；锗锡激光器的研究则集中在降低激射阈值、提高激射温度和电泵浦方面。本文还对锗铅材料和光电器件的研究进展进行简要介绍和展望。随着硅基高效光源和探测器研究的不断深入，IV族合金材料在硅基红外光电集成领域将继续展现重要的应用价值。