School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
Nano Lett. 2012 Sep 12;12(9):4953-9. doi: 10.1021/nl302558b. Epub 2012 Sep 4.
Stacking of two-dimensional electron gases (2DEGs) obtained by δ-doping of Ge and patterned by scanning probe lithography is a promising approach to realize ultrascaled 3D epitaxial circuits, where multiple layers of active electronic components are integrated both vertically and horizontally. We use atom probe tomography and magnetotransport to correlate the real space 3D atomic distribution of dopants in the crystal with the quantum correction to the conductivity observed at low temperatures, probing if closely stacked δ-layers in Ge behave as independent 2DEGs. We find that at a separation of 9 nm the stacked-2DEGs, while interacting, still maintain their individuality in terms of electron transport and show long phase coherence lengths (∼220 nm). Strong vertical electron confinement is crucial to this finding, resulting in an interlayer scattering time much longer (∼1000 × ) than the scattering time within the dopant plane.
通过对 Ge 进行 δ 掺杂并通过扫描探针光刻进行图案化而获得的二维电子气 (2DEG) 的堆叠是实现超小型 3D 外延电路的一种很有前途的方法，其中多个层的有源电子组件在垂直和水平方向上都得到了集成。我们使用原子探针断层扫描和磁输运来将晶体中掺杂剂的实空间 3D 原子分布与在低温下观察到的电导率量子修正相关联，以探测在 Ge 中紧密堆叠的 δ 层是否表现为独立的 2DEG。我们发现，在 9nm 的间隔下，堆叠的 2DEG 虽然相互作用，但在电子输运方面仍保持其个体性，并表现出长的相位相干长度（220nm）。强的垂直电子限制对于这一发现至关重要，导致层间散射时间比掺杂剂平面内的散射时间长得多（1000×）。
