原子层沉积二氧化钛提高氮化镓纳米线的光电化学光探测稳定性

TiO;-assisted GaN-nanowire-based stable ultraviolet photoelectrochemical detection

紫外光探测在光通信、化学与生物相关传感应用中发挥着重要作用。基于氮化镓纳米线的光电化学光探测器以其自供能、环境敏感等特性受到广泛关注。然而,氮化镓纳米线在光电化学环境中易受到光腐蚀,极不稳定。为了提高氮化镓纳米线在光电化学环境中的稳定性,在研究了氮化镓纳米线的光电化学光探测性质的基础上,提出一种利用原子层沉积技术在纳米线表面均匀包覆一层超薄的(~4 nm)二氧化钛保护层,以改善氮化镓纳米线的光电化学稳定性的方法。实验结果表明,相较于未被包覆的氮化镓纳米线,被二氧化钛保护层包覆的氮化镓纳米线在365 nm紫外光照下的光电流密度在2000 s的测试时间内的衰减程度有所下降。具体而言,未被包覆的氮化镓纳米线的光电流衰减系数高达85%;而包覆了二氧化钛保护层的氮化镓纳米线的光电流衰减系数可降至49%。该研究成果为构建长期稳定的氮化镓纳米线基光电化学型光探测器提供了参考。

Ultraviolet photodetection plays an important role in optical communication and chemical-and bio-related sensing applications.Gallium nitride(GaN)nanowires-based photoelectrochemical-type photodetectors,which operate particularly in acqueous conditions,have been attracted extensive interest because of their low cost,fast photoresponse,and excellent responsivity.However,GaN nanowires,which have a large surface-to-volume ratio,suffer suffered from instability in photoelectrochemical environments because of photocorrosion.In this study,the structural and photoelectrochemical properties of GaN nanowires with improved photoresponse and chemical stability obtained by coating the nanowire surface with an ultrathin TiO;protective layer were investigated.The photocurrent density of TiO;-coated GaN nanowires changed minimally over a relatively long operation time of 2000 s under 365-nm illumination.Meanwhile,the attenuation coefficient of the photocurrent density could be reduced to 49%,whereas it is as high as 85%in uncoated GaN nanowires.Furthermore,the photoelectrochemical behavior of the nanowires was investigated through electrochemical impedance spectroscopy measurements.The results shed light on the construction of long-term-stable GaN-nanowirebased photoelectrochemical-type photodetectors.