†Walter Schottky Institut, Physik Department, and Center of Nanotechnology and Nanomaterials, Technische Universität München, Garching 85748, Germany.
‡Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60201, United States.
Nano Lett. 2015 May 13;15(5):3295-302. doi: 10.1021/acs.nanolett.5b00518. Epub 2015 May 1.
Strong surface and impurity scattering in III-V semiconductor-based nanowires (NW) degrade the performance of electronic devices, requiring refined concepts for controlling charge carrier conductivity. Here, we demonstrate remote Si delta (δ)-doping of radial GaAs-AlGaAs core-shell NWs that unambiguously exhibit a strongly confined electron gas with enhanced low-temperature field-effect mobilities up to 5 × 10(3) cm(2) V(-1) s(-1). The spatial separation between the high-mobility free electron gas at the NW core-shell interface and the Si dopants in the shell is directly verified by atom probe tomographic (APT) analysis, band-profile calculations, and transport characterization in advanced field-effect transistor (FET) geometries, demonstrating powerful control over the free electron gas density and conductivity. Multigated NW-FETs allow us to spatially resolve channel width- and crystal phase-dependent variations in electron gas density and mobility along single NW-FETs. Notably, dc output and transfer characteristics of these n-type depletion mode NW-FETs reveal excellent drain current saturation and record low subthreshold slopes of 70 mV/dec at on/off ratios >10(4)-10(5) at room temperature.
在基于 III-V 族半导体的纳米线（NW）中，强烈的表面和杂质散射会降低电子器件的性能，因此需要精细的概念来控制载流子电导率。在这里，我们演示了径向 GaAs-AlGaAs 核壳 NW 的远程 Si δ（δ）掺杂，该掺杂明确表现出强受限电子气，低温场效应迁移率高达 5×10(3)cm(2)V(-1)s(-1)。通过原子探针断层扫描（APT）分析、能带轮廓计算和先进场效应晶体管（FET）结构中的传输特性，直接验证了 NW 核壳界面处的高迁移率自由电子气与壳层中 Si 掺杂剂之间的空间分离，从而实现了对自由电子气密度和电导率的有效控制。多栅 NW-FET 使我们能够在单个 NW-FET 上空间分辨出与通道宽度和晶体相相关的电子气密度和迁移率的变化。值得注意的是，这些 n 型耗尽模式 NW-FET 的直流输出和传输特性揭示了出色的漏极电流饱和，并且在室温下，记录到的亚阈值斜率低至 70mV/dec，导通/关断比大于 10(4)-10(5)。
