Ex situ characterization techniques in molecular beam epitaxy (MBE) have inherent limitations, such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber. In recent years, the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques. These techniques, such as reflection high-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, allow direct observation of film growth processes in real time without exposing the sample to air, hence offering insights into the growth mechanisms of epitaxial films with controlled properties. By combining multiple in situ characterization techniques with MBE, researchers can better understand film growth processes, realizing novel materials with customized properties and extensive applications. This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research. In addition, through further analysis of these techniques regarding their challenges and potential solutions, particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information, we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

在（211）B碲锌镉衬底上，采用分子束外延生长制备了PPP型中长双色碲镉汞材料，通过台面孔刻蚀、侧壁钝化等工艺，实现中长双色640×512 红外焦平面探测器组件研制。中长双色碲镉汞材料测试结果表明，表面宏观缺陷（2~10 μm）密度统计分布约773 cm^-2，同时对材料进行了XRD双晶衍射半峰宽（FWHM）测试和位错腐蚀坑（EPD）统计，XRD测试FWHM约31.9 arcsec，EPD统计值约为5×10⁵_{cm^-2；双色器件芯片台面刻蚀深度达到8 μm以上，深宽比达到1∶1以上，侧壁覆盖率达到72.5%。中长双色红外焦平面组件测试结果表明，中波波长响应范围为3.6~5.0 μm，长波波长响应范围为7.4~9.7 μm，中波向长波的串音为0.9 %，长波向中波的串音为3.1 %，中波平均峰值探测率达到3.31×10¹¹ cm·Hz^1/2/W，NETD为17.7 mK；长波平均峰值探测率达到6.52×10¹⁰ cm·Hz^1/2/W，NETD为32.8 mK；中波有效像元率达到99.46%，长波有效像元率达到98.19 %，初步实现中长双色红外焦平面组件研制。}

研究了分子束外延生长条件对高铟组分InGaAs材料性能的影响，分析了生长温度、V/III比和As分子束形态对In_0.74Ga_0.26As材料光致发光和X射线衍射峰强度、本底载流子浓度和迁移率的影响。测试结果表明：适中的生长温度和V/III比可以提高材料晶格质量，减少非辐射复合，降低本底杂质浓度。As分子束为As₂时In_0.74Ga_0.26As材料质量优于As₄分子束。当生长温度为570 ℃，As分子束形态为As₂，V/III比为18时，可以获得较高的光致发光和X射线衍射峰强度，室温和77 K下的本底载流子浓度分别达到6.3×10¹⁴ cm^-3和4.0×10¹⁴ cm^-3，迁移率分别达到13 400 cm²/Vs和45 160 cm²/Vs。

利用分子束外延技术在GaSb衬底上生长了高质量的InAs/InAsSb（无Ga）Ⅱ类超晶格。超晶格的结构由100个周期组成，每个周期分别是3.8 nm厚的InAs层和1.4 nm厚的InAs_0.66Sb_0.34层。在实验过程中出现了一种特殊的尖峰状缺陷。利用高分辨率x射线衍射（HRXRD）、原子力显微镜（AFM）和傅里叶变换红外光谱（FTIR）对外延的超晶格进行了表征和分析。结果表明，优化后的样品几乎为零晶格失配，超晶格0级峰半峰宽为39.3 arcsec，表面均方根粗糙度在10 μm×10 μm范围内达到1.72 ?。红外吸收光谱显示50%的截止波长为4.28 μm，PL谱显示InAs/InAs_0.66Sb_0.34超晶格4.58 μm处有清晰锐利的发光峰。这些结果表明，外延生长的InAs/InAsSb超晶格稳定性和重复性良好，值得进一步的研究。

用分子束外延系统（MBE）生长高质量GaSb基AlInAsSb四元数字合金制作雪崩光电二极管（APD）。为了克服随机体材料生长方式发生的偏析现象，采用迁移增强的数字合金生长方式，其快门顺序为AlSb，AlAs，AlSb，Sb，In，InAs，In，Sb。其高分辨率X射线衍射（HRXRD）曲线显示出尖锐的卫星峰，并显示出几乎完美的晶格匹配，其原子力显微镜（AFM）图像上也可以观察到光滑的表面形貌。使用优化的数字合金生长方式，制备了分离吸收、渐变、电荷和倍增（SAGCM）型的AlInAsSb数字合金APD。在室温下，器件在95%击穿时，暗电流密度为0.95 mA/cm²，击穿前最大稳定增益高达~100，其器件的高性能显示出光电领域进一步发展的潜力。