Laboratoire de Microscopies et d'Etude de Nanostructures (EA 3799), Bâtiment 6, case no 15, UFR Sciences, Université de Reims Champagne Ardenne, Reims Cedex 2, France.
Nanotechnology. 2010 Feb 10;21(6):065706. doi: 10.1088/0957-4484/21/6/065706. Epub 2010 Jan 8.
A combined conductive atomic force microscope (C-AFM)/scanning electron microscope (SEM) has been used to study the electric transport and retention mechanisms through Ge nanocrystals (NCs). The NCs were formed by a two-step dewetting/nucleation process on a silicon oxide layer grown on n-doped 001 silicon substrate. Without preliminary e-beam irradiation, electric images are obtained only with bias voltages larger than 8 V. This is due to the barrier height introduced by the presence of the native oxide on NCs and of the oxide layer on which the NCs are grown. After acquisition of an e-beam-induced current image, electric images (e-beam off) can be easily obtained at low bias voltages because of the trap creation in the oxide layer. We show that the critical threshold voltage to detect a current through the NCs decreases with NCs size. The band diagram of the contact in the presence of a p-doped diamond coated tip shows that the conduction mechanism is dominated by holes. At last we show a good memory effect with charge/discharge in the NCs resulting in a long retention time.
已经使用组合式导电原子力显微镜（C-AFM）/扫描电子显微镜（SEM）研究了通过锗纳米晶体（NCs）的电传输和保持机制。NCs 通过在氧化层上进行的两步去湿/成核过程在 n 型掺杂的 001 硅衬底上形成。在没有初步电子束辐照的情况下，仅在偏置电压大于 8V 时才能获得电图像。这是由于 NCs 上存在本征氧化物和生长 NCs 的氧化物层引入的势垒高度所致。在获得电子束诱导电流图像之后，由于在氧化物层中产生了陷阱，可以很容易地在低偏置电压下获得电图像（电子束关闭）。我们表明，检测通过 NCs 的电流的临界阈值电压随 NCs 尺寸的减小而减小。存在涂有 p 型金刚石尖端的接触的能带图表明，导电机制主要由空穴控制。最后，我们展示了 NCs 中电荷/放电的良好记忆效应，导致长时间的保持时间。
