Heavily doped semiconductors and devices

Abram, R. A.; Rees, G.J.; Wilson, B.L.H.

doi:10.1080/00018737800101484

Cited by 309 publications

(107 citation statements)

References 196 publications

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“…A large blue shift of the exciton absorption was observed in the UV-Vis diffuse reflectance spectrum of (Er, F) co-doped SnO 2 (Figure 6a) and the estimated band gap by the Kubelka-Munk function analysis was 4.18 eV (Figure 6c). The shift could be due to the combined effect of quantum size and the Moss-Burstein effects [43,44]. Additional experiments on the variation of absorption edge with temperature can provide crucial information on thermal activation threshold of this co-doped system as its shape is greatly influenced by the carrier-phonon interaction and the carrier-impurity interactions with increasing temperature.…”

Section: Resultsmentioning

confidence: 99%

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

Kumar¹,

Uma²,

Nagarajan³

2014

Turk J Phys

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Uniformly (Er, F) co-doped SnO 2 nanocrystals, obtained by a low-temperature solution-based method, were characterized by a variety of analytical techniques. The structure, morphology, and ratio of the elements were confirmed by PXRD, SEM, and TEM analysis, respectively. From XPS analysis, atomic concentrations of Sn, O, and F were quantified. Interparticle pore size increased significantly (with a mean pore diameter of 25.82 nm) in the codoped sample. Higher in-plane oxygen vacancies and bands due to multiphonon scattering were observed in the Raman spectrum of the sample. The defect traps in the sample were experimentally determined using TL spectroscopy. A broad intense glow curve at 485 K and a weak emission at 600 K in the TL spectrum were quenched on exposure to UV radiation. A large blue shift of the exciton absorption (due to the Moss-Burstein effect) and sharp bands due to intraconfigurational f − f transitions were observed for (Er, F) co-doped SnO 2 with an estimated band gap of 4.18 eV.From the photoluminescence spectral studies, 3 types of emission centers at 471 nm, 546 nm, and 627 nm were detected.Co-doping stabilized ferromagnetism in SnO 2 at room temperature.

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Section: Resultsmentioning

confidence: 99%

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

Kumar¹,

Uma²,

Nagarajan³

2014

Turk J Phys

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“…It only depends weakly on n el even though both E 1 and E 2 vary with n el noticeably. This variation arises mainly from the mutual exchange and Coulomb interactions between the electrons which show up as an effective increase in the energy of the defects [29,30]. The Coulomb interactions among the electrons themselves lead to the lowering of the energy of the conduction band by approximately [29],…”

Section: Resultsmentioning

confidence: 99%

Electrical transport properties of single-crystalCaB6,SrB6, andBaB
Stankiewicz
¹
,
Rosa
²
,
Schlottmann
³

et al. 2016
Phys. Rev. B

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The electrical resistivity and Hall effect of alkaline-earth-metal hexaboride single crystals are measured as a function of temperature, hydrostatic pressure, and magnetic field. The transport properties vary weakly with the external parameters and are modeled in terms of intrinsic variable-valence defects. These defects can stay either in (1) delocalized shallow levels or in (2) localized levels resonant with the conduction band, which can be neutral or negatively charged. Satisfactory agreement is obtained for electronic transport properties in a broad temperature and pressure range, although fitting the magnetoresistance is less straightforward and a combination of various mechanisms is needed to explain the field and temperature dependences.

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“…The quantities of interest are the bandgap E g is reduced by 800 meV, while E 11 B is reduced by 590 meV. Both of these changes are large by any measure; in particular we estimate that band gap renormalization (BGR) is about an order of magnitude larger than in typical bulk semiconductors at the same doping [14]. The QP bands and exciton level associated with the second lowest prominent optical transition (E 22 , not shown in Fig.…”

mentioning

confidence: 98%

Tunable Band Gaps and Excitons in Doped Semiconducting Carbon Nanotubes Made Possible by Acoustic Plasmons

2010

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Doping of semiconductors is essential in modern electronic and photonic devices. While doping is well understood in bulk semiconductors, the advent of carbon nanotubes and nanowires for nanoelectronic and nanophotonic applications raises some key questions about the role and impact of doping at low dimensionality. Here we show that for semiconducting carbon nanotubes, bandgaps and exciton binding energies can be dramatically reduced upon experimentally relevant doping, and can be tuned gradually over a broad range of energies in contrast to higher dimensional systems. The later feature is made possible by a novel mechanism involving strong dynamical screening effects mediated by acoustic plasmons.Nanomaterials have been lauded for their promise in electronic and photonic applications [1]. Quite often, the imagined nanodevices rely on analogies with those based on bulk semiconductors. However, the true potential of nanomaterials lies in the exploitation of their unique properties to realize entirely new device concepts. In particular, approaches for externally controlling their electronic and optical properties would enable new strategies for device design.Here we propose that such control is possible in carbon nanotubes (CNTs) through electrostatic doping. We find that quasiparticle (QP) band gaps and exciton binding energies can be reduced dramatically by hundreds of meVs upon doping, and yet prominent optical absorption features shift by relatively small amounts. Furthermore, we show that doping has a unique influence on CNT exciton properties: in contrast to bulk excitons, bound excitons in semiconducting CNTs are not quenched by doping and their binding energy can be tuned gradually even at very high doping. These features arise due to the presence of acoustic plasmons and their impact on dynamical screening.We utilize a many-body ab initio approach [2-4] to calculate the electronic and optical properties of electrostatically doped semiconducting CNTs. We focus on the semiconducting (10,0) CNT, with diameter D = 0.78 nm, and perform ab initio calculations [5] at zero doping and for a free carrier concentration ρ = 0.6 holes/nm. We use the GW approach [2] to obtain QP properties near the Γ point and solve the Bethe-Salpeter (BS) equation for the excitonic effects [3]. Applying this approach to doped CNTs necessitates careful consideration because of the presence of acoustic plasmons, a unique feature of low-dimensionality materials [6,7].Indeed, in quasi-1D systems such as CNTs, electron gas and tight-binding models predict "acoustic" plasmons, whose energies approach zero in the long wavelength limitω ap (q → 0) ∝ q ρ log(|q|D/2). Our ab initio calculations also reveal these plasmons in doped CNTs [8]: Fig. 1a shows the inverse dielectric function ε −1 00 (q = 0.35 nm −1 , E) of the (10,0) CNT at ρ = 0.6 holes/nm. The peak in Imε −1 signals a low-energy plasmon, which gives rise to a transition in Reε −1 between a very small value at zero energy and a value close to 1 above the plasmon energy, i.e. a transit...

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Heavily doped semiconductors and devices

Cited by 309 publications

References 196 publications

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

Electrical transport properties of single-crystalCaB6,SrB6, andBaB
Stankiewicz
¹
,
Rosa
²
,
Schlottmann
³

et al. 2016
Phys. Rev. B

Tunable Band Gaps and Excitons in Doped Semiconducting Carbon Nanotubes Made Possible by Acoustic Plasmons

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Heavily doped semiconductors and devices

Cited by 309 publications

References 196 publications

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

Optical and magnetic properties of (Er, F) co-doped SnO$_{2}$ nanocrystals

Electrical transport properties of single-crystalCaB6,SrB6, andBaBStankiewicz1, Rosa2, Schlottmann3 et al. 2016Phys. Rev. B

Tunable Band Gaps and Excitons in Doped Semiconducting Carbon Nanotubes Made Possible by Acoustic Plasmons

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Product

Resources

About

Electrical transport properties of single-crystalCaB6,SrB6, andBaB
Stankiewicz
¹
,
Rosa
²
,
Schlottmann
³

et al. 2016
Phys. Rev. B