采用飞秒激光加工4H-SiC压力敏感膜片，研究了飞秒激光深度方向步进间距、扫描路径方向、单脉冲能量、扫描线间距等参数对4H-SiC烧蚀形貌和烧蚀速率的影响。实验结果表明，飞秒激光加工4H-SiC样品表面孔洞的形成主要与激光诱导微沟槽的重叠有关，激光能量分布更均匀能够有效减少4H-SiC被烧蚀表面的激光诱导微沟槽的数量，增大激光扫描路径与激光偏振方向的夹角能够有效降低激光诱导微沟槽的重叠概率，从而抑制孔洞的形成。采用优化后的飞秒激光加工工艺参数，制备出直径为1 600 μm、厚度为100 μm的4H-SiC压力敏感膜片。所制备的4H-SiC压力敏感膜片表面无明显孔洞，边缘过烧蚀深度小于10 μm，实现了4H-SiC压力敏感膜片的低损伤飞秒激光加工。

Solar-blind ultraviolet photodetectors (SBPDs) have attracted tremendous attention in the environmental, industrial, military, and biological fields. Aluminum gallium nitride (AlGaN), a kind of representative III-nitride semiconductor, has promising prospects in solar-blind photodetection owing to its tunable wide bandgap and industrial feasibility. Considering the high defect density in the AlGaN epilayer directly grown on a sapphire substrate, employing an AlN/sapphire template turns out to be an effective method to achieve a high-quality AlGaN epilayer, thereby enhancing the SBPD performances. In recent years, a variety of remarkable breakthroughs have been achieved in the SBPDs. In this paper, the progress on photovoltaic AlGaN-based SBPDs is reviewed. First, the basic physical properties of AlGaN are introduced. Then, fabrication methods and defect annihilation of the AlN/sapphire template are discussed. Various photovoltaic SBPDs are further summarized, including Schottky barrier, metal-semiconductor-metal, p-n/p-i-n and avalanche photodiodes. Furthermore, surface modification and photoelectrochemical cell techniques are introduced. Benefitting from the development of fabrication techniques and optoelectronic devices, photovoltaic AlGaN photodiodes exhibit a promising prospect in solar-blind ultraviolet photodetection.