Yang Wang, Cheng Chen, Ziming Tang, Huan Lu, Shuiyan Cao, Wei Zhang, Min Yi, Kai Zhang, Yanpeng Liu, Wanlin Guo

Science China Materials  ，2023 ，66， 2364–2371.

Abstract: Multilayer black phosphorus (BP) has been widely used in many infrared applications due to its narrow bandgap below 3.7-µm wavelength range. Approaches that reduce the bandgap to less than 0.33 eV would extend the cutoff wavelength and are of paramount importance. Moreover, the poor air stability of BP severely limits its practical applications. However, none of the current methods ensure effective bandgap tuning while enhancing air stability of BP for long-term device operation. This paper solved both problems by substituting BP with congener arsenic (As) atoms. We achieved millimeter-sized As-substituted BP (b-AsxP1−x) by optimizing the chemical vapor transport parameters, with As concentrations (x) varying as 0, 0.3, 0.4, 0.5, and 0.6. According to the scanning tunneling microscopy results, arsenic atoms are resolved to be randomly embedded in the phosphorus host lattice, while maintaining a well-ordered lattice arrangement. Therefore, the electrical bandgap of pristine BP is narrowed to ∼0.16 ± 0.02 eV for the b-As0.6P0.4 sample, accompanied by the accumulated p-doping and red-shifting BP Raman feature. Furthermore, the device based on b-As0.6P0.4 exhibits no signs of oxidation under ambient conditions (temperature ∼20°C; humidity ∼33%) for 48 h and shows a photoresponsivity of up to ∼882 mA W−1, exceeding the values of ∼314 mA W−1 for pristine BP devices due to the strong doping without obvious lattice distortion. Our findings indicate that arsenic-substituted BP has potential application in developing ambient-stable photodetectors and optical modulators.

摘要：多层黑磷的带隙(~0.33 eV)覆盖~3.7微米光谱范围, 在红外应用 方面有巨大潜力. 然而进一步降低带隙使其可用于远红外器件仍面临 挑战. 此外, 黑磷材料及器件饱受空气稳定性差的困扰. 因此, 我们提 出了同系物砷取代的策略, 实现了对黑磷带隙的调控和稳定性的增强. 通过优化化学气相传输的生长参数, 我们制备出砷含量可控的毫米级 黑磷母体. 经扫描隧道显微镜和能谱分析, 砷原子随机嵌入黑磷的主晶 格中并保留了原有几近完美的晶格排列. 对于60%砷含量的多层黑磷, 其电学带隙降低至~0.16 ± 0.02 eV并伴随强的p型掺杂. 受益于较小的 晶格畸变和强掺杂效应, 基于砷取代黑磷的光电器件表现出高达约 8 8 2 mA W−1 的光响应率, 远超未取代的黑磷基光电器件(约 314 mA W−1). 更为重要的是, 砷取代的黑磷器件在暴露大气环境(温度 ~20°C; 湿度~33%) 48小时后未表现出明显的氧化迹象. 本文为开发黑 磷基、可长时间运行的光电探测器和光调制器件提供了新途径.

Link: https://link.springer.com/article/10.1007/s40843-022-2347-9