Wang Yaqian, Wu Yabo, Liang Fei, Wang Xuping, Yu Haohai, Zhang Huaijin, Wu Yicheng
State Key Laboratory of Crystal Materials and Institute of Crystal Materials, Shandong University, Jinan, 250100, China.
Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi, 830011, China.
Adv Sci (Weinh). 2025 Feb;12(6):e2412877. doi: 10.1002/advs.202412877. Epub 2024 Dec 17.
Photoelectric conversion in ferroelectric crystals can support many important applications in modern on-chip technology, but suffering from two problems, low responsive current and narrow responsive range. Especially, wide-gap ferroelectric oxides are only active at short-wavelength ultraviolet region with weak photocurrent at nanoampere levels. Here, a bifunctional design strategy of ferroelectric-order and electronic-band to improve the photocurrent and extend the responsive range simultaneously, is proposed. In a Cu-doped KTa NbO (KTN) perovskite crystal, a conductive channel is constructed by "head-to-head" ferroelectric domains, associated with the emergence of micrometer-scale supercells. In addition, the introduction of Cu ion can induce defect levels, thus extending the responsive range beyond the inherent absorption of pure KTN. Through rational device optimization, a record self-powered responsivity of 5.23 mA W is realized in Cu:KTN photodetector, which is two orders of magnitude higher than undoped KTN crystal. The temperature-dependent light diffraction and photocurrent show that the ferroelectric-order is dominated in this photoresponse behavior. Moreover, Cu:KTN detector is active in the broadband range from 390 to 1030 nm, covering ultraviolet, visible, and near-infrared regions. This work provides an effective method for the design of next-generation self-powered photodetectors with ultrahigh responsivity and ultrawide responsive range.
铁电晶体中的光电转换可支持现代片上技术中的许多重要应用，但存在两个问题，即响应电流低和响应范围窄。特别是，宽带隙铁电氧化物仅在短波长紫外区域有活性，光电流微弱，处于纳安水平。在此，提出了一种铁电序和电子能带的双功能设计策略，以同时提高光电流并扩展响应范围。在一种铜掺杂的铌酸钾钠（KTN）钙钛矿晶体中，通过“头对头”铁电畴构建了一个导电通道，这与微米级超晶胞的出现有关。此外，铜离子的引入可诱导缺陷能级，从而将响应范围扩展到纯KTN的固有吸收范围之外。通过合理的器件优化，在铜掺杂KTN光电探测器中实现了5.23 mA/W的创纪录自供电响应度，比未掺杂的KTN晶体高出两个数量级。与温度相关的光衍射和光电流表明，铁电序在这种光响应行为中起主导作用。此外，铜掺杂KTN探测器在390至1030 nm的宽带范围内有活性，覆盖紫外、可见和近红外区域。这项工作为设计具有超高响应度和超宽响应范围的下一代自供电光电探测器提供了一种有效方法。
