A new theoretical method to study super-multiperiod superlattices has been developed. The method combines the precision of the 8-band kp-method with the flexibility of the shooting method and the Monte Carlo approach. This method was applied to examine the finest quality samples of super-multiperiod Al_0.3Ga_0.7As/GaAs superlattices grown by molecular beam epitaxy. The express photoreflectance spectroscopy method was utilized to validate the proposed theoretical method. For the first time, the accurate theoretical analysis of the energy band diagram of super-multiperiod superlattices with experimental verification has been conducted. The proposed approach highly accurately determines transition peak positions and enables the calculation of the energy band diagram, transition energies, relaxation rates, and gain estimation. It has achieved a remarkably low 5% error compared to the commonly used method, which typically results in a 25% error, and allowed to recover the superlattice parameters. The retrieved intrinsic parameters of the samples aligned with XRD data and growth parameters. The proposed method also accurately predicted the escape of the second energy level for quantum well thicknesses less than 5 nm, as was observed in photoreflectance experiments. The new designs of THz light-emitting devices operating at room temperature were suggested by the developed method.

In this paper, we demonstrate nBn InAs/InAsSb type II superlattice (T2SL) photodetectors with AlAsSb as the barrier that targets mid-wavelength infrared (MWIR) detection. To improve operating temperature and suppress dark current, a specific Sb soaking technique was employed to improve the interface abruptness of the superlattice with device passivation using a SiO2 layer. These result in ultralow dark current density of 6.28×10-6A/cm2 and 0.31A/cm2 under -600mV at 97 K and 297 K, respectively, which is lower than most reported InAs/InAsSb-based MWIR photodetectors. Corresponding resistance area product values of 3.20×104Ω·cm2 and 1.32Ω·cm2 were obtained at 97 K and 297 K. A peak responsivity of 0.39 A/W with a cutoff wavelength around 5.5 µm and a peak detectivity of 2.1×109cm·Hz1/2/W were obtained at a high operating temperature up to 237 K.

II类超晶格红外探测器一般通过台面结实现对红外辐射的探测，而通过离子注入实现横向PN结，一方面材料外延工艺简单，同时可以利用超晶格材料横向扩散长度远高于纵向的优势改善光生载流子的输运，且易于制作高密度平面型阵列。本文利用多种材料表征技术，研究了不同能量的Si离子注入以及退火前后对InAs/GaSb II类超晶格材料性能的影响。研究通过Si离子注入，外延材料由P型变为N型，超晶格材料中产生了垂直方向的拉伸应变，晶格常数变大，且失配度随着注入能量的增大而增大，注入前失配度为-0.012%，当注入能量到200 keV时，失配度达到0.072%，超晶格部分弛豫，弛豫程度为14%，而在300 °C 60 s退火后，超晶格恢复完全应变状态，且晶格常数变小，这种张应变是退火引起的Ga-In相互扩散以及Si替位导致的晶格收缩而造成的。

带间级联红外探测器可以利用多级吸收区级联的方式实现高的工作温度，但不同的吸收区厚度设计方式会使得器件在不同级数吸收区中出现光生载流子的不匹配现象，从而对器件量子效率造成影响。为更好地理解带间级联探测器的级数和吸收区厚度对量子效率的影响，对基于InAs/GaSb II类超晶格的带间级联探测器进行了变温测试，并基于多级光电流的“平均效应”建立了工作在反向偏置电压的量子效率计算模型，通过与实际测试的量子效率对比，发现在低温条件下实验数据和计算结果拟合一致性较好，验证了多级带间级联探测器中基于内增益机制的光电流平均效应。但在高温条件下，实际的光电流低于“平均效应”的理论计算结果，这可能是由于高温下少数载流子寿命变短，在吸收区和弛豫区界面处存在光生载流子的复合机制。

非线性频率转换是非线性光学中的重点研究内容之一，本文将Gosper分形与Z分形两种超晶格结构引入非线性光子晶体中，理论分析了两种超晶格结构经过准相位匹配进行非线性频率转换的谐波特点。Gosper分形超晶格的倒空间结构整体旋转60°后，依然能够和原图形重合；在准相位匹配的条件下，能够在六个不同方向实现相同的倍频波长输出；在级联三倍频中，实现了波长为711.3 nm、554.7 nm、491 nm的三倍频输出，并理论计算了其偏离角度。在二维Z分形的傅里叶空间中，充分利用了高阶横向倒格矢，能够实现基波波长范围为1.402 μm~1.430 μm的二次谐波频率转换，其中波长间距最小仅有1 nm。最后，为三维Z分形超晶格结构晶体的制备提供了数据支持。

Efficient and eco-friendly disinfection of air-borne human respiratory RNA viruses is pursued in both public environment and portable usage. The AlGaN-based deep ultraviolet (DUV) light-emission diode (LED) has high practical potentials because of its advantages of variable wavelength, rapid sterilization, environmental protection, and miniaturization. Therefore, whether the emission wavelength has effects on the disinfection as well as whether the device is feasible to sterilize various respiratory RNA viruses under portable conditions is crucial. Here, we fabricate AlGaN-based DUV LEDs with different wavelength on high-temperature-annealed (HTA) AlN/Sapphire templates and investigate the inactivation effects for several respiratory RNA viruses. The AlN/AlGaN superlattices are employed between the template and upper n-AlGaN to release the strong compressive stress (SCS), improving the crystal quality and interface roughness. DUV LEDs with the wavelength of 256, 265, and 278 nm, corresponding to the light output power of 6.8, 9.6, and 12.5 mW, are realized, among which the 256 nm-LED shows the most potent inactivation effect in human respiratory RNA viruses, including SARS-CoV-2, influenza A virus (IAV), and human parainfluenza virus (HPIV), at a similar light power density (LPD) of ~0.8 mW/cm² for 10 s. These results will contribute to the advanced DUV LED application of disinfecting viruses with high potency and broad spectrum in a portable and eco-friendly use.

双波段红外探测可对复杂的红外背景进行抑制，在军用目标识别、医疗诊断和污染监测等方面有重要应用价值。基于二类超晶格的双波段红外探测器在成本和性能方面具有很大的优势，成为新型红外探测器领域的研究热点。然而其暗电流和串扰会极大地影响双波段红外探测器的性能。因此，设计了nBn结构的InAs/GaSb超晶格中/长波双波段红外探测器，通过仿真比较不同结构的器件在不同偏压下的中波/长波通道的响应率和暗电流大小，分析势垒层厚度、吸收层厚度、不同区域的掺杂对暗电流和串扰的影响，从而得到最佳的模型参数达到减小暗电流和降低串扰的效果。仿真结果显示：nBn结构的中/长波双波段红外探测器在77 K下，中波通道的暗电流密度为4.5×10⁻⁵ A·cm⁻²，在0.3 V偏压下，2 µm处的峰值量子效率为64%，探测率可以达到3.9×10¹¹ cm·Hz^1/2·W⁻¹；长波通道的暗电流密度为1.3×10⁻⁴ A·cm⁻²，在−0.3 V的偏压下，5.6 µm处的峰值量子效率为48%，探测率可以达到4.1×10¹¹ cm·Hz^1/2·W⁻¹。相关结论可为器件设计和加工提供参考。