Charge collection scanning electron microscopy

Leamy, H. J.

doi:10.1063/1.331667

Cited by 772 publications

(343 citation statements)

References 172 publications

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“…Both will contribute to free charge carrier population and minimize the exciton population in the measurement at hand (and in the actual working device). Variations in EBIC contrast reflect the dynamics of the carrier lifetime 9,13 . The intense signal close to the HTM-CH 3 NH 3 PbI 3 À x Cl x interface indicates efficient hole extraction.…”

Section: Resultsmentioning

confidence: 99%

Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells

et al. 2014

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Developments in organic-inorganic lead halide-based perovskite solar cells have been meteoric over the last 2 years, with small-area efficiencies surpassing 15%. We address the fundamental issue of how these cells work by applying a scanning electron microscopy-based technique to cell cross-sections. By mapping the variation in efficiency of charge separation and collection in the cross-sections, we show the presence of two prime high efficiency locations, one at/near the absorber/hole-blocking-layer, and the second at/near the absorber/electron-blocking-layer interfaces, with the former more pronounced. This 'twin-peaks' profile is characteristic of a p-i-n solar cell, with a layer of low-doped, high electronic quality semiconductor, between a p-and an n-layer. If the electron blocker is replaced by a gold contact, only a heterojunction at the absorber/hole-blocking interface remains.

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Section: Resultsmentioning

confidence: 99%

Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells

et al. 2014

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“…20 The electron beam of the SEM is scanning over the sample, inducing electron-hole pairs in the semiconductor. In absence of an electric field, these eventually recombine.…”

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confidence: 99%

Axial p-n Junctions Realized in Silicon Nanowires by Ion Implantation

et al. 2009

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The electrical properties of vertically aligned silicon nanowires doped by ion implantation are studied in this paper by a combination of electron beam-induced current imaging and two terminal current-voltage measurements. By varying the implantation parameters in several process steps, uniform p-and n-doping profiles as well as p-n junctions along the nanowire axis are realized. The effective doping is demonstrated by electron beam-induced current imaging on single nanowires, and current-voltage measurements show their well-defined rectifying behavior.Semiconductor nanowires are expected to play a critical role in future electronic devices and sensors. 1 To make use of their semiconducting properties, doping is an important issue. Nanowires that form an epitaxial interface and thus are vertically aligned to the substrate are commonly grown by the vapor-liquid-solid (VLS) mechanism in which a metal catalyst forms eutectic droplets at the growing tips of the nanowires. 2 For silicon nanowires, a supply of Si vapor supersaturates these droplets with Si and leads to its precipitation at the liquid-solid (droplet-silicon) interface. Under the gold droplet, the nanowire grows as long as the Si vapor is present. Silicon nanowires reveal p-type conductance when they are grown using the VLS process without adding any dopant on purpose, but the resistivity is rather high (2 Ω cm 3 -400 Ω cm 4 ).Doping can be realized during the gas phase deposition process by adding dopants to the gas mixture in use for the nanowire growth. Dopant incorporation is reported for diborane, 4 trimethylboron, 5 phosphine, 3 and arsenic. 6 By changing the dopant source during growth, p-n junctions can be realized along the axis of the nanowire. 6,7 Little is known on the dopant incorporation mechanism, however. Therefore, it is not obvious to predict the doping concentration for a given process. Also, recent experimental results reveal the growth of a highly doped shell around the nanowire while doping during VLS growth. 8 As an alternative, reproducible and successful doping of nanowires can be achieved via ion implantation. This technique is a standard doping technique in top-down semiconductor manufacturing and offers the advantage to provide for precise control over the total dose of dopants, depth profile, and most importantly works well also for high doping levels of the order of 10 20 -10 21 cm -3 . It has been demonstrated that GaAs can be p-type doped using Zn ions, and Si by the respective use of B and P ions. 10 The latter work presents field effect transistors based on ion-implanted nanowires. However, the demonstration of ion-implanted nanowires acting as devices by themselves is still lacking. Masking selected parts of the sample at different implantation steps, the doping profile can be chosen to be different from nanowire to nanowire. This is an additional advantage over doping during growth, or etching nanowires out of a doped wafer, as for both these methods all nanowires reveal the same doping concentration. This pap...

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“…The electron-beam acceleration voltage V acc was 10 kV. Since the lateral size of excitation volume was proportional to the V acc 1.75 , 12 the low acceleration voltage is preferable to improve the measurement resolution. On the other hand, an electron-beam with a low acceleration voltage will produce electron-hole pairs close to the surface, making the effect of surface recombination worse.…”

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confidence: 99%

Minority carrier diffusion length in GaN: Dislocation density and doping concentration dependence

et al. 2005

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We investigated the minority carrier diffusion length in p-and n-GaN by performing electron-beam-induced current measurements of GaN p -n junction diodes. Minority electron diffusion length in p-GaN strongly depended on the Mg doping concentration for relatively low dislocation density below 10 8 cm −2 . It increased from 220 to 950 nm with decreasing Mg doping concentration from 3 ϫ 10 19 to 4 ϫ 10 18 cm −3 . For relatively high dislocation density above 10 9 cm −2 , it was less than 300 nm and independent of the Mg doping concentration. On the other hand, the minority hole diffusion length in n-GaN was shorter than 250 nm and less affected by the dislocation density and Si doping concentration. We discuss the doping-concentration and dislocation-density dependence of minority carrier diffusion length.

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Charge collection scanning electron microscopy

Cited by 772 publications

References 172 publications

Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells

Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells

Axial p-n Junctions Realized in Silicon Nanowires by Ion Implantation

Minority carrier diffusion length in GaN: Dislocation density and doping concentration dependence

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