Self-Purification in Semiconductor Nanocrystals

Dalpian, Gustavo M.; Chelikowsky, James R.

doi:10.1103/physrevlett.96.226802

Cited by 641 publications

(485 citation statements)

References 25 publications

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“…Surface segregation of impurities [6,20,21] during growth will enhance η even further. More important, however, is the large number of FX transitions.…”

Section: Resultsmentioning

confidence: 99%

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

et al. 2010

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Single, free-standing GaN nanowires grown by plasma-assisted molecular-beam epitaxy have been investigated with low temperature micro-photoluminescence. The quantitative analysis of the luminescence spectra of around 100 nanowires revealed that each nanowire exhibits its own individual spectrum. A significant fraction of nanowires exclusively emits at energies corresponding to either surface-donor-bound or free excitons, demonstrating that optical properties of individual nanowires are determined by a few impurity atoms alone. The number of impurities per nanowire and their location within the nanowires varies according to Poissonian statistics.

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“…Surface segregation of impurities [6,20,21] during growth will enhance η even further. More important, however, is the large number of FX transitions.…”

Section: Resultsmentioning

confidence: 99%

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

et al. 2010

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“…Dopants can be introduced in well-defined concentrations during the growth of bulk crystal (1), yet in synthesized nanoscale structures, such as nanoparticles and NWs, the incorporation of dopants during growth may be affected by kinetic and thermodynamic factors associated with finite size (3)(4)(5)(6)(7)(8)(9). Difficulties in incorporating dopants into nanoparticles have been attributed to surface energetics within the context of the kinetics for colloidal growth (3,4) and thermodynamic factors during high-temperature growth (5). In the case of synthesized semiconductor nanowires, there is considerable evidence from electrical transport measurements that active dopants can be incorporated during growth (6)(7)(8)(9).…”

mentioning

confidence: 99%

Diameter-dependent dopant location in silicon and germanium nanowires

Xie

Fang

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

109

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We report studies defining the diameter-dependent location of electrically active dopants in silicon (Si) and germanium (Ge) nanowires (NWs) prepared by nanocluster catalyzed vapor-liquidsolid (VLS) growth without measurable competing homogeneous decomposition and surface overcoating. The location of active dopants was assessed from electrical transport measurements before and after removal of controlled thicknesses of material from NW surfaces by low-temperature chemical oxidation and etching. These measurements show a well-defined transition from bulk-like to surface doping as the diameter is decreased <22-25 nm for nand p-type Si NWs, although the surface dopant concentration is also enriched in the larger diameter Si NWs. Similar diameterdependent results were also observed for n-type Ge NWs, suggesting that surface dopant segregation may be general for small diameter NWs synthesized by the VLS approach. Natural surface doping of small diameter semiconductor NWs is distinct from many top-down fabricated NWs, explains enhanced transport properties of these NWs and could yield robust properties in ultrasmall devices often dominated by random dopant fluctuations.nanoelectronics ͉ surface doping ͉ surface segregation ͉ vapor-liquid-solid growth

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“…The formation energy of defects in nanocrystals increases as the size of the nanocrystals decreases [27]. The surface dangling bond states that lie within the band-gap typically quench the PL intensity.…”

Section: Methodsmentioning

confidence: 99%

Passivated ZnSe nanocrystals prepared by hydrothermal methods and their optical properties

et al. 2010

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Homogeneous ZnSe nanocrystals were prepared via surfactant-assisted hydrothermal method. Surfactants agent CTAB was used to control the particle morphology and the growth rate. The structure, morphology and optical properties of ZnSe nanocrystals have been investigated by XRD, TEM and luminescence spectroscopy. The results indicated that the size of ZnSe nanocrystals ranged from 3.0 nm to 5.0 nm with cubic zinc blende structure. ZnSe nanocrystals coated by CTAB were revealed high dispersibility and distribution under TEM. Compared to the bulk ZnSe, the absorption edges and photoluminescence peaks of ZnSe nanocrystals were blue shifted to higher energies due to the quantum confinement effect. The emission intensity was strengthened after coated CTAB compared to bare sample. This was mainly due to the surface passivation. Meanwhile, we simply explored the formation mechanism of ZnSe nanocrystal in hydrothermal system. Keywords: Zinc selenide; Nanocrystals; Surface passivatiom; Photoluminescence Citation: Lingling Peng, Yuhua Wang, Qizheng Dong and Zhaofeng Wang, "Passivated ZnSe nanocrystals prepared by hydrothermal methods and their optical properties", Nano-Micro Lett. 2, 190-196 (2010). doi:10.5101/nml.v2i3. p190-196 Semiconductor nanocrystals (NCs), or quantum dots (QDs), have been extensively studied due to their quantum confinement effects which exhibit unique size dependent electronic and optical properties [1,2]. Narrow and intensive emission spectra, continuous absorption bands, high chemical and photobleaching stability, and surface functionality are among the most attractive properties of these materials, which are not available from either bulk materials or isolated atoms. At present, synthetic procedures have been developed for a few group II-VI and III-V.As one of the Zn-based II-VI compounds, ZnSe is a direct band-gap semiconductor, with one room-temperature band-gap energy and an emission at 2.7 eV making it a potentially good material for blue-diode lasers and other photoelectronic devices [12,13] were also reported. However, all of these methods required special device and usually included toxic metal organic reagents as raw material [14]. It is believed that the most straightforward way to synthesize ZnSe is direct combination of element zinc and selenium at high temperature.Li et al has reported a successful fabrication of ZnSe by hydrothermal method in specific solvents such as pyridine which is virulent, so it must be synthesized at glove-box [15]. Hua Gong et al once reported analogy method at low-temperature and the products presented hollow microsphere and powder [16]. In hydrothermal syntheses, reaction time, temperature, and mole ratios of the precursors and solvent were very important to the Lingling Peng et al 191Nano -Micro Lett. 2, 190-196 (2010) Experimental procedureThe starting materials were Se (99.95% A.R.), Zn (90% A.R.), NaOH (96% A.R.), and cetyl trimethy ammonium bromide (CTAB). 12 mol/L NaOH aqueous solutions was poured into a bunsen beaker, and then CTAB was adde...

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Self-Purification in Semiconductor Nanocrystals

Cited by 641 publications

References 25 publications

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the poissonian limit

Diameter-dependent dopant location in silicon and germanium nanowires

Passivated ZnSe nanocrystals prepared by hydrothermal methods and their optical properties

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