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.

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.

A new kind of step-flow growth mode is proposed, which adopts sidewall as step source on patterned GaN substrate. The terrace width of steps originated from the sidewall was found to change with the growth temperature and ammonia flux. The growth mechanism is explained and simulated based on step motion model. This work helps better understand the behaviors of step advancement and puts forward a method of precisely modulating atomic steps.

利用金属有机化合物化学气相沉积（MOCVD）技术，在不同晶面的蓝宝石（Al₂O₃）衬底上实现了极性（0002）面、半极性（11-22）面和非极性（11-20）面InN薄膜的外延生长，并通过多种表征手段对三个不同极性面InN薄膜的结构和光学特性进行了系统研究。X射线衍射（XRD）曲线展示了（0002）、（11-22）和（11-20）面InN较强的衍射峰，表明InN薄膜具有较高的成膜质量。通过扫描电子显微镜（SEM）表面图发现，极性（0002）面InN的表面形貌较光滑，而半极性和非极性InN表面均存在未完全合并的孔洞。光致发光（PL）光谱展示，不同极性面InN的峰值能量在0.63 eV附近，并从极性、半极性到非极性逐渐红移。此外，可见-红外分光光度计测得的透射谱显示，极性（0002）面InN的吸收边约为0.85 eV，而半极性（11-22）面和非极性（11-20）面InN的吸收边约为0.78 eV，表明极性InN具有更大的斯托克斯位移。

在铜基金属卤化物Cs₃Cu₂I₅中掺杂Mn²⁺是拓宽发光范围的重要途径，但是已报道的掺杂方法大多需要高温、惰性气氛、较长时间和专用设备等。本工作将CsI固体粉末直接投加至CuI和MnCl₂的氢碘酸溶液中，在较低温度（60 ℃）、空气条件下快速（3 min）合成Mn²⁺掺杂Cs₃Cu₂I₅微晶，并测试了其结构和发光性能。通过系列对比实验，提出一种由反应物溶解度控制的“缓释生长-掺杂”机制，证实CsI固体粉末在高浓度氢碘酸中的缓慢溶解能够降低Cs₃Cu₂I₅晶体的生长速率，为Mn²⁺的低温、可控掺杂提供有利的动力学条件。该方法为全无机金属卤化物体系的掺杂发光和掺杂动力学研究提供了新的思路。

通过分析牙釉质化石自然样品的电子自旋共振（Electron Spin Resonance，ESR）信号强度，可以构建牙釉质标准生长曲线（Standardised Growth Curve，SGC），用以直接获得样品等效剂量（D_E）值。但由于不同时段的化石样品石化程度不同，其剂量响应特征也不尽相同，很难建立统一的化石标准生长曲线。本研究通过对32个中晚更新世阶段牙釉质样品ESR信号分析发现，这一时段的样品具有近似的剂量响应，因此在前期工作的基础上尝试采用三种不同方法构建晚更新世化石样品的标准生长曲线，并将获得的化石样品等效剂量与附加剂量法的结果进行了比较，最小偏差在26%内。本文还探讨了建立化石样品标准生长曲线的潜在优势。

Palladium (Pd)-based sulfides have triggered extensive interest due to their unique properties and potential applications in the fields of electronics and optoelectronics. However, the synthesis of large-scale uniform PdS and PdS₂ nanofilms (NFs) remains an enormous challenge. In this work, 2-inch wafer-scale PdS and PdS₂ NFs with excellent stability can be controllably prepared via chemical vapor deposition combined with electron beam evaporation technique. The thickness of the pre-deposited Pd film and the sulfurization temperature are critical for the precise synthesis of PdS and PdS₂ NFs. A corresponding growth mechanism has been proposed based on our experimental results and Gibbs free energy calculations. The electrical transport properties of PdS and PdS₂ NFs were explored by conductive atomic force microscopy. Our findings have achieved the controllable growth of PdS and PdS₂ NFs, which may provide a pathway to facilitate PdS and PdS₂ based applications for next-generation high performance optoelectronic devices.