Nathabumroong S, Eknapakul T, Jaiban P, Yotburut B, Siriroj S, Saisopa T, Mo S-K, Supruangnet R, Nakajima H, Yimnirun R, Maensiri S, Meevasana W
School of Physics and Center of Excellence on Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand.
Faculty of science, Energy and Environment, King Mongkut's University of Technology North Bangkok, Rayong Campus, Rayong, 21120, Thailand.
Sci Rep. 2020 Mar 20;10(1):5153. doi: 10.1038/s41598-020-61859-6.
Light-sensitive capacitance variation of BiLaFeO (BLFO) ceramics has been studied under violet to UV irradiation. The reversible capacitance enhancement up to 21% under 405 nm violet laser irradiation has been observed, suggesting a possible degree of freedom to dynamically control this in high dielectric materials for light-sensitive capacitance applications. By using ultraviolet photoemission spectroscopy (UPS), we show here that exposure of BLFO surfaces to UV light induces a counterintuitive shift of the O valence state to lower binding energy of up to 243 meV which is a direct signature of negative electronic compressibility (NEC). A decrease of BLFO electrical resistance agrees strongly with the UPS data suggesting the creation of a thin conductive layer on its insulating bulk under light irradiation. By exploiting the quantum capacitance model, we find that the negative quantum capacitance due to this NEC effect plays an important role in this capacitance enhancement.
对BiLaFeO（BLFO）陶瓷在紫光到紫外光照射下的光敏电容变化进行了研究。在405 nm紫光激光照射下，观察到可逆电容增强高达21%，这表明在高介电材料中动态控制用于光敏电容应用的这种特性存在一种可能的自由度。通过使用紫外光电子能谱（UPS），我们在此表明，BLFO表面暴露于紫外光会导致O价态向更低结合能发生高达243 meV的反直觉偏移，这是负电子压缩性（NEC）的直接特征。BLFO电阻的降低与UPS数据高度吻合，表明在光照射下其绝缘块体上形成了一个薄导电层。通过利用量子电容模型，我们发现由于这种NEC效应产生的负量子电容在这种电容增强中起着重要作用。
