为了提高红外探测器的工作温度，基于InAs/GaSb II类超晶格材料设计了一种五级带间级联结构中波红外光电探测器，并采用分子束外延技术和标准化光刻及刻蚀技术进行了器件的制备。在77 K时，该器件的50%截止波长是4.02 μm，在0 V时峰值探测率为1.26×10¹² cm·Hz^1/2/W；在300 K零偏压下，该器件的50%截止波长是4.88 μm，峰值探测率为1.28×10⁹ cm·Hz^1/2/W，实现了高温探测。从180 K到300 K，器件的暗电流主要由扩散电流主导。在77 K到220 K温度范围的暗电流曲线中观察到了负微分电阻现象，并解释了峰谷电流比相对于温度变化的趋势。研究结果表明，具有带间级联结构的T2SL探测器可以进行室温工作，在中波范围内有比较明显的优势。

We report on a long wavelength interband cascade photodetector with type II InAs/GaSb superlattice absorber. The device is a three-stage interband cascade structure. At 77 K, the 50% cutoff wavelength of the detector is 8.48 μm and the peak photoresponse wavelength is 7.78 μm. The peak responsivity is 0.93 A/W and the detectivity D* is 1.12 × 10¹¹ cm·Hz^0.5/W for 7.78 μm at –0.20 V. The detector can operate up to about 260 K. At 260 K, the 50% cutoff wavelength is 11.52 μm, the peak responsivity is 0.78 A/W and the D* is 5.02 × 10⁸ cm·Hz^0.5/W for the peak wavelength of 10.39 μm at –2.75 V. The dark current of the device is dominated by the diffusion current under both a small bias voltage of –0.2 V and a large one of –2.75 V for the temperature range of 120 to 260 K.We report on a long wavelength interband cascade photodetector with type II InAs/GaSb superlattice absorber. The device is a three-stage interband cascade structure. At 77 K, the 50% cutoff wavelength of the detector is 8.48 μm and the peak photoresponse wavelength is 7.78 μm. The peak responsivity is 0.93 A/W and the detectivity D* is 1.12 × 10¹¹ cm·Hz^0.5/W for 7.78 μm at –0.20 V. The detector can operate up to about 260 K. At 260 K, the 50% cutoff wavelength is 11.52 μm, the peak responsivity is 0.78 A/W and the D* is 5.02 × 10⁸ cm·Hz^0.5/W for the peak wavelength of 10.39 μm at –2.75 V. The dark current of the device is dominated by the diffusion current under both a small bias voltage of –0.2 V and a large one of –2.75 V for the temperature range of 120 to 260 K.

Moiré superlattices are formed when overlaying two materials with a slight mismatch in twist angle or lattice constant. They provide a novel platform for the study of strong electronic correlations and non-trivial band topology, where emergent phenomena such as correlated insulating states, unconventional superconductivity, and quantum anomalous Hall effect are discovered. In this review, we focus on the semiconducting transition metal dichalcogenides (TMDs) based moiré systems that host intriguing flat-band physics. We first review the exfoliation methods of two-dimensional materials and the fabrication technique of their moiré structures. Secondly, we overview the progress of the optically excited moiré excitons, which render the main discovery in the early experiments on TMD moiré systems. We then introduce the formation mechanism of flat bands and their potential in the quantum simulation of the Hubbard model with tunable doping, degeneracies, and correlation strength. Finally, we briefly discuss the challenges and future perspectives of this field.Moiré superlattices are formed when overlaying two materials with a slight mismatch in twist angle or lattice constant. They provide a novel platform for the study of strong electronic correlations and non-trivial band topology, where emergent phenomena such as correlated insulating states, unconventional superconductivity, and quantum anomalous Hall effect are discovered. In this review, we focus on the semiconducting transition metal dichalcogenides (TMDs) based moiré systems that host intriguing flat-band physics. We first review the exfoliation methods of two-dimensional materials and the fabrication technique of their moiré structures. Secondly, we overview the progress of the optically excited moiré excitons, which render the main discovery in the early experiments on TMD moiré systems. We then introduce the formation mechanism of flat bands and their potential in the quantum simulation of the Hubbard model with tunable doping, degeneracies, and correlation strength. Finally, we briefly discuss the challenges and future perspectives of this field.

提出了采用金属有机化学气相沉积（MOCVD）生长无Ga且应力平衡的InAsP/InAsSb超晶格，并探索了其作为红外吸收材料的可行性。首先采用k·p理论计算了InAsP/InAsSb超晶格的带隙，发现其波长调节范围可以从中波红外到长波红外。然后通过MOCVD技术在InAs衬底上生长了InAs_0.8P_0.2/InAs_0.7Sb_0.3超晶格。XRD测试结果表明，InAs衬底峰与超晶格零级卫星峰的失配仅61"，即基本实现应力平衡；AFM测试材料表面形貌显示5 μm×5 μm范围内均方根粗糙度为0.4 nm；低温PL光谱显示较强的发光，峰位于3.3 μm的中波红外波段，接近设计值。这些结果表明采用MOCVD生长应力平衡的InAsP/InAsSb超晶格作为红外探测材料具有较好的可行性和实用性。

近零等效介电常数超材料以其近乎等于零的等效介电常数所赋予的电磁特性使其在理论研究和工程应用中均有可观的价值，是电磁超材料领域研究热点之一。本文系统总结了为了解决现有近零介电常数超材料工作频率单一的不足，以等效介质理论的Bergman-Milton谱表述理论为基础，结合超材料典型微观结构等效介电常数谱表述的特点，建立宽频近零介电常数超材料的谱表述理论，并以此为基础设计具有宽频近零介电常数超材料的研究成果。理论上，对超材料的材料特性和微观结构特性抽象化，实现了对具备超晶格构型的宽频近零介电常数超材料的快速建构，解释了宽频近零介电常数的物理原理，并获得了数值模拟的验证。同时，在应用方面，根据宽频近零介电常数超材料的物理特性，突出展示了所设计的宽频近零介电常数超材料在宽频电磁隧穿与聚焦、宽频电磁波定向发射、宽频电磁波波前调制等方面的应用。