Stavarache Ionel, Palade Catalin, Slav Adrian, Dascalescu Ioana, Lepadatu Ana-Maria, Matei Elena, Besleaga Cristina, Ciurea Magdalena Lidia, Kardynal Beata E, Stoica Toma
National Institute of Materials Physics 405A Atomistilor Street 077125 Magurele Romania
Academy of Romanian Scientists 54 Splaiul Independentei 050094 Bucharest Romania.
Nanoscale Adv. 2025 Feb 24;7(8):2368-2380. doi: 10.1039/d5na00138b. eCollection 2025 Apr 8.
The gas sensitivity of field-effect structures with 2D-MoS channels selectively grown between Mo electrodes using the Mo-CVD method was investigated by measuring the effect of molecular adsorption from air on the device source-drain current ( ). The channels were composed of interconnected atomically thin MoS grains, with their density and average thickness varied by choosing two different distances (15 and 20 μm) between the Mo contacts. A high response to the tested stimuli, including molecule adsorption, illumination and gate voltage changes, was observed. A significant, persistent photoconduction was induced by positive charge accumulation on traps, most likely at grain boundaries and associated defects. increased under high vacuum, both in the dark and under illumination. The relative dark current response to the transition from air to high vacuum reached up to 1000% at the turn-on voltage. When monitored during the gradual change in air pressure, exhibited a non-monotonic function, sharply peaking at about 10 mbar, suggesting molecular adsorption on different defect sites and orientations of adsorbed HO molecules, which were capable of inducing electron accumulation or depletion. Despite the screening of disorder by extra electrons, the #20 μm sample remained more sensitive to air molecules on its surface. The high vacuum state was also investigated by annealing devices at temperatures up to 340 K in high vacuum, followed by measurements down to 100 K. This revealed thermally stimulated currents and activation energies of trapping electronic states assigned to sulfur vacancies (230 meV) and other shallow levels (85-120 meV), possibly due to natural impurities, grain boundaries or disorder defects. The results demonstrate the high sensitivity of these devices to molecular adsorption, making the technology promising for the easy fabrication of chemical sensors.
通过测量空气中分子吸附对器件源漏电流（ ）的影响，研究了采用钼化学气相沉积（Mo-CVD）方法在钼电极之间选择性生长二维硫化钼（2D-MoS）通道的场效应结构的气敏特性。这些通道由相互连接的原子级薄的硫化钼晶粒组成，通过选择钼接触之间的两个不同距离（15和20μm）来改变其密度和平均厚度。观察到对包括分子吸附、光照和栅极电压变化在内的测试刺激有高响应。由陷阱上的正电荷积累（最有可能在晶界和相关缺陷处）诱导出显著的、持续的光电导。在高真空下，无论是在黑暗中还是光照下， 都增加。在开启电压下，从空气到高真空转变的相对暗电流响应高达1000%。当在气压逐渐变化过程中进行监测时， 呈现出非单调函数，在约10毫巴处急剧峰值，表明分子吸附在不同的缺陷位点以及吸附的羟基分子的不同取向上，这些能够诱导电子积累或耗尽。尽管额外电子对无序进行了屏蔽，但20μm的样品对其表面的空气分子仍更敏感。还通过在高真空下将器件在高达340K的温度下退火，然后测量至100K来研究高真空状态。这揭示了热激发电流以及归因于硫空位（230毫电子伏）和其他浅能级（85 - 120毫电子伏）的俘获电子态的激活能，这可能是由于天然杂质、晶界或无序缺陷所致。结果表明这些器件对分子吸附具有高灵敏度，使得该技术在易于制造化学传感器方面具有前景。
