Diameter-Dependent Electron Mobility of InAs Nanowires

Ford, Alexandra C.; Ho, Johnny C.; Chueh, Yu‐Lun; Tseng, Yu‐Chih; Fan, Zhiyong; Guo, Jing; Bokor, Jeffrey; Javey, Ali

doi:10.1021/nl803154m

Cited by 368 publications

(427 citation statements)

References 35 publications

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“…The mobility starts to saturate at lower temperature at which point it becomes limited by scattering events related to the nanowire structure including planar defects. 15 Similar trends have been observed previously in InAs films, 42 InAs nanowires 15 and InAs-InP 43 and InAs-InAlAs 44 core-shell nanowires. Here we consider three different candidate mechanisms that could be causing this marked increase in mobility with antimony content: (i) the different intrinsic electrical properties of InAs 1−x Sb x as a function of Sb content; (ii) the different electrical properties of the WZ and ZB polytypes of InAs 1−x Sb x ; and (iii) the variation of the planar defect density.…”

Section: Electrical Transport In Inas 1−x Sb X Nanowiressupporting

confidence: 76%

Mobility Enhancement by Sb-mediated Minimisation of Stacking Fault Density in InAs Nanowires Grown on Silicon

et al. 2014

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We report the growth of InAs 1−x Sb x nanowires (0 ≤ x ≤ 0.15) grown by catalyst-free molecular beam epitaxy on silicon (111) substrates. We observed a sharp decrease of stacking fault density in the InAs 1−x Sb x nanowire crystal structure with increasing antimony content. This decrease leads to a significant increase in the field-effect mobility, this being more than three times greater at room temperature for InAs 0.85 Sb 0.15 nanowires than InAs nanowires. * To whom correspondence should be addressed † London Centre for Nanotechnology, University College London, London WC1H 0AH, United Kingdom ‡ Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom 1 arXiv:1402.3489v1 [cond-mat.mtrl-sci] Feb 2014Semiconductor nanowires are leading candidates for future applications in a wide variety of electronic, photonic and sensing devices. 1,2 III-V compound semiconductor nanowires including InAs 3 and GaN 4,5 have a number of potential functional advantages over elemental semiconductor nanowires including high mobility and direct bandgap. Furthermore the magnitude of the bandgap can be modulated by exploiting ternary compound semiconductors (such as InAsP 6 and AlGaAs 7 ), allowing the creation of heterostructure nanowires with axially-or radially-modulated electronic properties. Such bandgap engineering is in principle a more powerful tool for nanowire-based devices than thin-film-based devices since the radial relaxation of strain in nanowires allows the growth of heterostructures whose constituent compounds are significantly lattice-mismatched. 8,9 The growth of compound semiconductor nanowires directly onto single crystal silicon wafers would be advantageous, 10,11 because (i) it would allow integration of nanowire devices with the established silicon CMOS technology; and (ii) silicon wafers are orders of magnitude cheaper than their compound semiconductor counterparts. Compound semiconductor nanowires are, however, typically grown using the "vapor-liquid-solid" technique in which gold nanoparticle catalysts seed the growth. Gold cannot be combined with silicon since it forms trap states in the silicon bandgap. 12-14 Nickel has also been used to catalyze InAs nanowire growth on silicon 15 but these nanowires are not functional for direct integration as they grow following random orientations with respect to the substrate. There have therefore been many reports of nanowire growth without the use of heterocatalytic nanoparticle seeds [16][17][18][19][20][21] . In the case of the widely-studied narrow-bandgap semiconductor InAs, however, the absence of a heterocatalyst results in the nanowires displaying very high densities of defects including stacking faults, twin boundaries and polytypism, i.e. uncontrolled axial modulation of the crystal structure between the zinc-blende (cubic) and the wurtzite (hexagonal) polytypes of InAs. 17,21 This in turn leads to an undesirable suppression of the electron mobility. 22 In this letter, we investigate an approa...

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Section: Electrical Transport In Inas 1−x Sb X Nanowiressupporting

confidence: 76%

Mobility Enhancement by Sb-mediated Minimisation of Stacking Fault Density in InAs Nanowires Grown on Silicon

et al. 2014

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“…The as-grown InAs NW is n-type due to the high electron concentration that results from surface fixed charges and local imbalances in stoichiometry. 16 As previously discussed, there is a linear dependence of the device resistance on channel length, establishing that the Ni source/drain contacts to the conduction band of as-grown InAs NWs are Ohmic. 7 The as-grown NW exhibits an ON current of ∼4.4 µA at V DS ) 0.5 V, I ON /I OFF > 10 4 , and field-effect mobility of 4400 cm 2 /(V s) for channel length L ) 8 µm and NW diameter d ) 27 nm, consistent with the previously published observation.…”

mentioning

confidence: 69%

“…7 The as-grown NW exhibits an ON current of ∼4.4 µA at V DS ) 0.5 V, I ON /I OFF > 10 4 , and field-effect mobility of 4400 cm 2 /(V s) for channel length L ) 8 µm and NW diameter d ) 27 nm, consistent with the previously published observation. 16 The doped InAs NWs using the described process conditions are p + due to heavy Zn doping, exhibiting an ON current of ∼0.4 µA at V DS ) 0.5 V with minimal gate dependence (Figure 2b). The linear behavior of the I DS -V DS plot (Figure 2b inset) confirms that the contacts to the p + NW are near Ohmic.…”

mentioning

confidence: 95%

Patterned p-Doping of InAs Nanowires by Gas-Phase Surface Diffusion of Zn

Ford

Chuang

et al. 2010

Nano Lett.

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Gas phase p-doping of InAs nanowires with Zn atoms is demonstrated as an effective route for enabling postgrowth dopant profiling of nanostructures. The versatility of the approach is demonstrated by the fabrication of high-performance gated diodes and p-MOSFETs. High Zn concentrations with electrically active content of ∼1 × 10 19 cm -3 are achieved which is essential for compensating the electron-rich surface layers of InAs to enable heavily p-doped structures. This work could have important practical implications for the fabrication of planar and nonplanar devices based on InAs and other III-V nanostructures which are not compatible with conventional ion implantation processes that often cause severe lattice damage with local stoichiometry imbalance.KEYWORDS Nanoscale doping, p-type MOSFETs, diodes, III-V nanowires, zinc dopants I n the endless trend to shrink transistor dimensions to increase density and performance, planar devices are reaching the threshold for many desirable device characteristics. 1 To this end, many other novel transistor structures are being explored. In particular, much research has been devoted to transistors with nanowire (NW) channels due to their excellent electrostatic properties. 2,3 One very promising semiconductor for NW devices is InAs, due to its excellent electron mobilities, 4-6 and ease of nanoscale, metal Ohmic contact formation to the conduction band via solid source reactions. 7 However, there remain many challenges to be addressed with InAs NW device fabrication. Specifically, one fabrication issue that requires attention is the dopant profiling of InAs NWs. p-type doping of InAs NWs is particularly challenging given the surface electron-rich layer that causes the surface Fermi level to be pinned in the conduction band for an undoped NW. Although techniques such as in situ doping during the growth have been previously reported for NWs, 8-10 postgrowth patterned doping is desired for most device fabrication schemes. Notably, conventional ion-implantation techniques are not compatible with nanoscale InAs semiconductors due to the severe crystal damage induced during the implantation process resulting in In atom clustering which cannot be fixed by a subsequent annealing process. In that regard, surface doping processes are highly attractive. [11][12][13] To address this need, here, we report patterned p-doping of InAs NWs with Zn atoms by using a postgrowth, surface doping approach. The versatility of the approach is demonstrated by configuring the doped NWs into various device structures, including p + -n diodes, and p-MOSFETs.InAs NWs used in this work were grown using the vapor-liquid-solid (VLS) method by chemical vapor deposition in a two-zone tube furnace using solid InAs powder source. As previously described, a 0.5 nm thick Ni film was annealed at 800°C for 10 min to create nanoparticles that serve as catalysts. 14 A substrate temperature of 490°C, source temperature of 720°C, and pressure of 5 Torr with H 2 carrier gas (200 SCCM flow rate) were used. The...

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“…2(c)); this suggests a five-fold drop in the conductivity on reducing the diameter from 120 to ~20 nm. The suggested [8] enhanced role of the electron surface scattering and surface transport in increasing the surface to volume ratio-which scales linearly with d-are among the important factors that may account for the observed linear decrease of the NW conductivity. This also is in accordance with the dramatic effect of surface oxidation on the conductivity, reported in the next section.…”

Section: Size-dependent Conductivity Of Gaas Nws and Temperature Effectsmentioning

confidence: 92%

“…The conductivity of NWs, one of the most important properties exploited in numerous applications, becomes extremely sensitive to the status of the surface with decreasing NW width, and dramatic conductivity changes can be observed when the Debye length becomes comparable to the NW radius [4]. Along with presence of adsorbates and charged surface states [5,6], other factors that may affect the conductivity include the (i) reduced mobility due to enhanced phonon or surface scattering [7,8], (ii) edge effects due to unsaturated bonds of the surface atoms [9], (iii) size-imposed limits to the effective doping concentration [9,10], (iv) size-dependence of depletion width [11], band-gaps [12,13], and recombination barriers [14]. As a result, significant scatter in the conductivity data are observed for individual GaAs NWs purportedly fabricated in the same manner [15].…”

Section: Introductionmentioning

confidence: 99%

Contactless monitoring of the diameter-dependent conductivity of GaAs nanowires

et al. 2010

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Contactless monitoring with photoelectron microspectroscopy of the surface potential along individual nanostructures, created by the X-ray nanoprobe, opens exciting possibilities to examine quantitatively size-and surface-chemistry-effects on the electrical transport of semiconductor nanowires (NWs). Implementing this novel approach-which combines surface chemical microanalysis with conductivity measurements-we explored the dependence of the electrical properties of undoped GaAs NWs on the NW width, temperature and surface chemistry. By following the evolution of the Ga 3d and As 3d core level spectra, we measured the positiondependent surface potential along the GaAs NWs as a function of NW diameter, decreasing from 120 to ~20 nm, and correlated the observed decrease of the conductivity with the monotonic reduction in the NW diameter from 120 to ~20 nm. Exposure of the GaAs NWs to oxygen ambient leads to a decrease in their conductivity by up to a factor of 10, attributed to the significant decrease in the carrier density associated with the formation of an oxide shell.

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Diameter-Dependent Electron Mobility of InAs Nanowires

Cited by 368 publications

References 35 publications

Mobility Enhancement by Sb-mediated Minimisation of Stacking Fault Density in InAs Nanowires Grown on Silicon

Mobility Enhancement by Sb-mediated Minimisation of Stacking Fault Density in InAs Nanowires Grown on Silicon

Patterned p-Doping of InAs Nanowires by Gas-Phase Surface Diffusion of Zn

Contactless monitoring of the diameter-dependent conductivity of GaAs nanowires

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