Gated transport measurements are the backbone of electrical characterization of nanoscale electronic devices. Scanning gate microscopy （SGM） is one such gating technique that adds crucial spatial information, access...Gated transport measurements are the backbone of electrical characterization of nanoscale electronic devices. Scanning gate microscopy （SGM） is one such gating technique that adds crucial spatial information, accessing the localized properties of semiconductor devices. Nanowires represent a central device concept due to the potential to combine very different materials. However, SGM on semiconductor nanowires has been limited to a resolution in the 50-100 nm range. Here, we present a study by SGM of newly developed III-V semiconductor nanowire InAs/GaSb heterojunction Esaki tunnel diode devices under ultra-high vacuum. Sub-5 nm resolution is demonstrated at room temperature via use of quartz resonator atomic force microscopy sensors, with the capability to resolve InAs nanowire facets, the InAs/GaSb tunnel diode transition and nanoscale defects on the device. We demonstrate that such measurements can rapidly give important insight into the device properties via use of a simplified physical model, without the requirement for extensive calculation of the electrostatics of the system. Interestingly, by precise spatial correlation of the device electrical transport properties and surface structure we show the position and existence of a very abrupt （〈10 nm） electrical transition across the InAs/GaSb junction despite the change in material composition occurring only over 30-50 nm. The direct and simultaneous link between nanostructure composition and electrical properties helps set important limits for the precision in structural control needed to achieve desired device performance.展开更多
Nanowires have many interesting properties that are of advantage for solar cells,such as the epitaxial combination of latticemismatched materials without plastic deformation.This could be utilized for the synthesis of...Nanowires have many interesting properties that are of advantage for solar cells,such as the epitaxial combination of latticemismatched materials without plastic deformation.This could be utilized for the synthesis of axial tandem-junction nanowire solar cells with high efficiency at low material cost.Electron-beam-induced current measurements have been used to optimize the performance of single-junction nanowire solar cells.Here,we use electron-beam-induced current measurements to break the barrier to photovoltaic tandem-junction nanowires.In particular,we identify and subsequently prevent the occurrence of a parasitic junction when combining an InP n-i-p junction with a tunnel diode.Furthermore,we demonstrate how to use optical and electrical biases to individually measure the electron-beam-induced current of both sub-cells of photovoltaic tandem-junction nanowires.We show that with an applied voltage in forward direction,all junctions can be analyzed simultaneously.The development of this characterization technique enables further optimization of tandem-junction nanowire solar cells.展开更多
通过测定雅氏山蝉(L ep top sa lta yam ash ita i(E sak i and Ish ihara),com b.nov.)若虫头壳宽度的方法,对雅氏山蝉若虫龄期划分进行了研究。采用标准地调查法,用频次比较法拟合,初步得出雅氏山蝉若虫共4龄。用若虫龄级与头宽均值...通过测定雅氏山蝉(L ep top sa lta yam ash ita i(E sak i and Ish ihara),com b.nov.)若虫头壳宽度的方法,对雅氏山蝉若虫龄期划分进行了研究。采用标准地调查法,用频次比较法拟合,初步得出雅氏山蝉若虫共4龄。用若虫龄级与头宽均值回归进行检验,证实了该蝉若虫共4龄。展开更多
文摘Gated transport measurements are the backbone of electrical characterization of nanoscale electronic devices. Scanning gate microscopy （SGM） is one such gating technique that adds crucial spatial information, accessing the localized properties of semiconductor devices. Nanowires represent a central device concept due to the potential to combine very different materials. However, SGM on semiconductor nanowires has been limited to a resolution in the 50-100 nm range. Here, we present a study by SGM of newly developed III-V semiconductor nanowire InAs/GaSb heterojunction Esaki tunnel diode devices under ultra-high vacuum. Sub-5 nm resolution is demonstrated at room temperature via use of quartz resonator atomic force microscopy sensors, with the capability to resolve InAs nanowire facets, the InAs/GaSb tunnel diode transition and nanoscale defects on the device. We demonstrate that such measurements can rapidly give important insight into the device properties via use of a simplified physical model, without the requirement for extensive calculation of the electrostatics of the system. Interestingly, by precise spatial correlation of the device electrical transport properties and surface structure we show the position and existence of a very abrupt （〈10 nm） electrical transition across the InAs/GaSb junction despite the change in material composition occurring only over 30-50 nm. The direct and simultaneous link between nanostructure composition and electrical properties helps set important limits for the precision in structural control needed to achieve desired device performance.
基金NanoLund,Myfab,the Swedish Energy Agency,Swedish Research council,and the Knut and Alice Wallenberg Foundation(No.2016-0089).
文摘Nanowires have many interesting properties that are of advantage for solar cells,such as the epitaxial combination of latticemismatched materials without plastic deformation.This could be utilized for the synthesis of axial tandem-junction nanowire solar cells with high efficiency at low material cost.Electron-beam-induced current measurements have been used to optimize the performance of single-junction nanowire solar cells.Here,we use electron-beam-induced current measurements to break the barrier to photovoltaic tandem-junction nanowires.In particular,we identify and subsequently prevent the occurrence of a parasitic junction when combining an InP n-i-p junction with a tunnel diode.Furthermore,we demonstrate how to use optical and electrical biases to individually measure the electron-beam-induced current of both sub-cells of photovoltaic tandem-junction nanowires.We show that with an applied voltage in forward direction,all junctions can be analyzed simultaneously.The development of this characterization technique enables further optimization of tandem-junction nanowire solar cells.
文摘通过测定雅氏山蝉(L ep top sa lta yam ash ita i(E sak i and Ish ihara),com b.nov.)若虫头壳宽度的方法,对雅氏山蝉若虫龄期划分进行了研究。采用标准地调查法,用频次比较法拟合,初步得出雅氏山蝉若虫共4龄。用若虫龄级与头宽均值回归进行检验,证实了该蝉若虫共4龄。
