A commercial epi-ready (2¯01) β-Ga₂O₃ wafer was investigated upon diamond sawing into pieces measuring 2.5 × 3 mm². The defect structure and crystallinity in the cut samples has been studied by X-ray diffraction and a selective wet etching technique. The density of defects was estimated from the average value of etch pits calculated, including near-edge regions, and was obtained close to 10⁹ cm⁻². Blocks with lattice orientation deviated by angles of 1−3 arcmin, as well as non-stoichiometric fractions with a relative strain about (1.0−1.5) × 10⁻⁴ in the [2¯01] direction, were found. Crystal perfection was shown to decrease significantly towards the cutting lines of the samples. To reduce the number of structural defects and increase the crystal perfection of the samples via increasing defect motion mobility, the thermal annealing was employed. Polygonization and formation of a mosaic structure coupled with dislocation wall appearance upon 3 h of annealing at 1100 °C was observed. The fractions characterized by non-stoichiometry phases and the block deviation disappeared. The annealing for 11 h improved the homogeneity and perfection in the crystals. The average density of the etch pits dropped down significantly to 8 × 10⁶ cm⁻².

日盲紫外探测器在**和民用领域均具有广阔的应用前景。基于宽禁带半导体材料的日盲紫外探测器具有无需昂贵的滤光片、工作电压低、全固态、体积小、重量轻、抗干扰能力强、工作温度范围广等特点，是公认的新一代紫外探测器。在众多的宽禁带半导体材料中，以Ga₂O₃作为典型代表的镓基氧化物材料因其优异的电学和光电特性已经成为近年来微电子学和光电子学领域的研究热点，特别是其本征日盲、耐高温、耐高压、化学稳定性好等优异特点使得该类材料在日盲紫外光电探测领域展现出巨大的发展潜力。鉴于此，本文综述了不同晶体结构的Ga₂O₃、镓酸盐氧化物、镓锡氧化物、镓铝氧化物等镓基氧化物薄膜及其日盲紫外探测器研究进展。

In the era of accelerated development in artificial intelligence as well as explosive growth of information and data throughput, underlying hardware devices that can integrate perception and memory while simultaneously offering the benefits of low power consumption and high transmission rates are particularly valuable. Neuromorphic devices inspired by the human brain are considered to be one of the most promising successors to the efficient in-sensory process. In this paper, a homojunction-based multi-functional optoelectronic synapse (MFOS) is proposed and testified. It enables a series of basic electrical synaptic plasticity, including paired-pulse facilitation/depression (PPF/PPD) and long-term promotion/depression (LTP/LTD). In addition, the synaptic behaviors induced by electrical signals could be instead achieved through optical signals, where its sensitivity to optical frequency allows the MFOS to simulate high-pass filtering applications in situ and the perception capability integrated into memory endows it with the information acquisition and processing functions as a visual system. Meanwhile, the MFOS exhibits its performances of associative learning and logic gates following the illumination with two different wavelengths. As a result, the proposed MFOS offers a solution for the realization of intelligent visual system and bionic electronic eye, and will provide more diverse application scenarios for future neuromorphic computing.

The anisotropic properties and applications of β-gallium oxide (β-Ga₂O₃) are comprehensively reviewed. All the anisotropic properties are essentially resulted from the anisotropic crystal structure. The process flow of how to exfoliate nanoflakes from bulk material is introduced. Anisotropic optical properties, including optical bandgap, Raman and photoluminescence characters are comprehensively reviewed. Three measurement configurations of angle-resolved polarized Raman spectra (ARPRS) are reviewed, with Raman intensity formulas calculated with Raman tensor elements. The method to obtain the Raman tensor elements of phonon modes through experimental fitting is also introduced. In addition, the anisotropy in electron mobility and affinity are discussed. The applications, especially polarization photodetectors, based on β-Ga₂O₃ were summarized comprehensively. Three kinds of polarization detection mechanisms based on material dichroism, 1D morphology and metal-grids are discussed in-depth. This review paper provides a framework for anisotropic optical and electric properties of β-Ga₂O₃, as well as the applications based on these characters, and is expected to lead to a wider discussion on this topic.

在250 ℃的低温下，以三甲基镓、四（二甲氨基）钛为前躯体源，O₃为反应气体，采用热原子层沉积制备了Ti掺杂Ga₂O₃（TGO）薄膜。Ga₂O₃和TiO₂的生长速率分别为0.037 nm/cycle和0.08 nm/cycle，TGO薄膜厚度低于理论计算值。X射线光电子能谱仪测试结果表明膜中Ti浓度随Ga₂O₃/TiO₂循环比减少而增加，O 1s、Ga 2p和Ti 2p的峰位置向较低的结合能移动，这是因为Ti原子取代了Ga原子的某些位点引起了结合能降低，表明Ti元素成功掺杂到Ga₂O₃薄膜中。TiO₂和Ga₂O₃的芯能级光谱分析表明薄膜中存有Ti⁴⁺和Ga³⁺离子。TGO薄膜的O 1s芯能级光谱中Ga-O键随着Ti-O键含量增加而下降，表明TGO薄膜中形成Ga₂O₃-TiO₂复合材料。掠入射X射线衍射图中没有出现衍射峰，表明沉积的Ga₂O₃和TGO薄膜为非晶态。原子力显微镜观察到薄膜表面平整光滑，均方根粗糙度为0.377 nm，这得益于原子层沉积逐层生长的优势。TGO薄膜在可见光区表现出较高的透明度，对紫外光强烈吸收。随着Ti掺杂浓度的增加，TGO薄膜的折射率由于化学变化从1.75增加到1.99，紫外光区消光系数增大引起透过率减小，吸收边缘出现了红移，光学带隙从4.9 eV减小到4.3 eV。分光光度法和X射线光电子能谱法测定薄膜光学带隙所得的结果一致。