Zhang Xiangzhe, Lv Bowen, Wei Haitao, Yan Xingheng, Peng Gang, Qin Shiqiao
College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China.
College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China.
Nanomaterials (Basel). 2024 Feb 25;14(5):422. doi: 10.3390/nano14050422.
Violet phosphorus (VP), a novel two-dimensional (2D) nanomaterial, boasts structural anisotropy, a tunable optical bandgap, and superior thermal stability compared with its allotropes. Its multifunctionality has sparked widespread interest in the community. Yet, the VP's air susceptibility impedes both probing its intrinsic features and device integration, thus making it of urgent significance to unveil the degradation mechanism. Herein, we conduct a comprehensive study of photoactivated degradation effects on VP. A nitrogen annealing method is presented for the effective elimination of surface adsorbates from VP, as evidenced by a giant surface-roughness improvement from 65.639 nm to 7.09 nm, enabling direct observation of the intrinsic morphology changes induced by photodegradation. Laser illumination demonstrates a significant thickness-thinning effect on VP, manifested in the remarkable morphological changes and the 73% quenching of PL intensity within 160 s, implying its great potential for the efficient selected-area etching of VP at high resolution. Furthermore, van der Waals passivation of VP using 2D hexagonal boron nitride (hBN) was achieved. The hBN-passivated channel exhibited improved surface roughness (0.512 nm), reduced photocurrent hysteresis, and lower responsivity (0.11 A/W @ 450 nm; 2 μW), effectively excluding adsorbate-induced electrical and optoelectrical effects while disabling photodegradation. Based on our experimental results, we conclude that three possible factors contribute to the photodegradation of VP: illumination with photon energy higher than the bandgap, adsorbed HO, and adsorbed O.
紫磷（VP）是一种新型二维（2D）纳米材料，具有结构各向异性、可调节的光学带隙，并且与其同素异形体相比具有优异的热稳定性。其多功能性引起了该领域的广泛关注。然而，VP对空气的敏感性阻碍了对其固有特性的探究以及器件集成，因此揭示其降解机制具有迫切的意义。在此，我们对VP的光激活降解效应进行了全面研究。提出了一种氮气退火方法来有效消除VP表面的吸附物，表面粗糙度从65.639 nm大幅改善至7.09 nm证明了这一点，从而能够直接观察光降解引起的固有形态变化。激光照射对VP表现出显著的厚度减薄效应，表现为明显的形态变化以及在160 s内PL强度淬灭73%，这意味着其在高分辨率下对VP进行高效选区蚀刻具有巨大潜力。此外，实现了使用二维六方氮化硼（hBN）对VP进行范德华钝化。hBN钝化的通道表现出改善的表面粗糙度（0.512 nm）、降低的光电流滞后和更低的响应度（450 nm、2 μW时为0.11 A/W），有效排除了吸附物引起的电学和光电效应，同时抑制了光降解。基于我们的实验结果，我们得出结论，VP光降解可能有三个因素：光子能量高于带隙的光照、吸附的HO和吸附的O。
