Lu Ming-Yen, Wu Shang-Chi, Wang Hsiang-Chen, Lu Ming-Pei
Department of Materials Science and Engineering and High Entropy Materials Center, National Tsing Hua University, Hsinchu 300, Taiwan.
Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Chia-Yi 62102, Taiwan.
Phys Chem Chem Phys. 2018 Apr 4;20(14):9038-9044. doi: 10.1039/C8CP00792F.
As the feature sizes of devices decrease to the nanoscale, electron microscopy and lithography will become increasingly essential techniques for fabrication and inspection. In this study, we probed the memory effects of MoS2 field-effect transistors (FETs) subjected to electron beam (e-beam) irradiation; after fabricating the devices on 300 nm SiO2/Si substrates, we irradiated the MoS2 FETs with various doses of irradiation from a 30 kV e-beam. The threshold voltage shifted to the negative side and the mobility increased-a so-called memory effect-upon increasing the e-beam dose. These changes resulted from positively charged oxide traps, formed upon e-beam irradiation, in the gate oxide layer. Interestingly, the electrical characteristics of the MoS2 FETs after e-beam irradiation continued to change upon aging: the threshold voltage shifted toward the positive side and the mobility decreased, suggesting that the dominant mechanism changed from the presence of positively charged oxide traps to the presence of negatively charged interface traps. Notably, the threshold voltage shifts of the MoS2 FETs could be retained for one or two days. This behavior should be useful for preparing property-adjustable nanodevices, with particular potential for applications in multi-level memory devices.
随着器件的特征尺寸缩小到纳米尺度，电子显微镜和光刻技术将成为制造和检测中越来越重要的技术。在本研究中，我们探究了经受电子束（e束）辐照的二硫化钼场效应晶体管（FET）的记忆效应；在300 nm SiO2/Si衬底上制造器件后，我们用30 kV的e束以不同剂量辐照二硫化钼FET。随着e束剂量增加，阈值电压向负向移动且迁移率增加——即所谓的记忆效应。这些变化是由e束辐照在栅氧化层中形成的带正电的氧化物陷阱导致的。有趣的是，e束辐照后的二硫化钼FET的电学特性在老化过程中持续变化：阈值电压向正向移动且迁移率降低，这表明主导机制从带正电的氧化物陷阱的存在转变为带负电的界面陷阱的存在。值得注意的是，二硫化钼FET的阈值电压偏移可以保持一到两天。这种行为对于制备性能可调的纳米器件应该是有用的，在多级存储器件中具有特别的应用潜力。
