Theory of Field Emission from Semiconductors

Stratton, R.

doi:10.1103/physrev.125.67

Cited by 252 publications

(77 citation statements)

References 23 publications

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“…For this purpose, we adapted expressions from Stratton. 50,51 Note that the complete conductivity model comprises of merely three fit parameters. The conductivity model and, in particular, the electron tunneling at grain boundaries will be described in more detail elsewhere.…”

Section: B Seed Layer: Temperature Variationmentioning

confidence: 99%

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Sommer

Stanley

Köhler

et al. 2015

Journal of Applied Physics

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This work elucidates the effect of the dopant aluminum on the growth of magnetron-sputtered aluminum-doped zinc oxide (ZnO:Al) films by means of a seed layer concept. Thin (<100 nm), highly doped seed layers and subsequently grown thick (∼800 nm), lowly doped bulk films were deposited using a ZnO:Al2O3 target with 2 wt. % and 1 wt. % Al2O3, respectively. We investigated the effect of bulk and seed layer deposition temperature as well as seed layer thickness on electrical, optical, and structural properties of ZnO:Al films. A reduction of deposition temperature by 100 °C was achieved without deteriorating conductivity, transparency, and etching morphology which renders these low-temperature films applicable as light-scattering front contact for thin-film silicon solar cells. Lowly doped bulk layers on highly doped seed layers showed smaller grains and lower surface roughness than their counterpart without seed layer. We attributed this observation to the beneficial role of the dopant aluminum that induces an enhanced surface diffusion length via a surfactant effect. The enhanced surface diffusion length promotes 2D-growth of the highly doped seed layer, which is then adopted by the subsequently grown and lowly doped bulk layer. Furthermore, we explained the seed layer induced increase of tensile stress on the basis of the grain boundary relaxation model. The model relates the grain size reduction to the tensile stress increase within the ZnO:Al films. Finally, temperature-dependent conductivity measurements, optical fits, and etching characteristics revealed that seed layers reduced grain boundary scattering. Thus, seed layers induced optimized grain boundary morphology with the result of a higher charge carrier mobility and more suitable etching characteristics. It is particularly compelling that we observed smaller grains to correlate with an enhanced charge carrier mobility. A seed layer thickness of 5 nm was sufficient to induce the beneficial effects.

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Section: B Seed Layer: Temperature Variationmentioning

confidence: 99%

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Sommer

Stanley

Köhler

et al. 2015

Journal of Applied Physics

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“…Unfortunately this caution does not seem to have been exercised by Good and Müller [3], nor by Murphy and Good [18]. The latter have derived widely used criteria [19] for the validity of FN theory on the basis of the WKB integrand properties equation (4) alone, which is thus a logically inadequate procedure. If we examine the classic FN formula for the emission current:…”

Section: Exact Solution Without Electron Imagesmentioning

confidence: 99%

“…These results clearly show that our theory has captured some essential physics associated to tunnelling near the barrier top which may be relevant to the carbon field emitters. ¶ Finite temperature effects should also be included in a more accurate calculation, providing essential improvements to thermionic field emission theory [18,19].…”

Section: Relation To Experimentsmentioning

confidence: 99%

Dynamical resonance tunnelling—a theory of giant emission from carbon field emitters

Choy¹,

Stoneham²,

Harker³

2005

J. Phys.: Condens. Matter

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Abstract. The classic theory of electron field emission from a cold metal surface due to Fowler and Nordheim (FN) is re-examined and found to violate the validity criteria for the WKB approximation, for electric fields greater than about 1 V/µm. In this study we shall examine the complete solution without invoking the WKB approximation in order to assess the reliability of the FN theory as widely used for the interpretation of experimental data. Particular problems occur when the barrier height (and therefore indirectly also the width) is significantly reduced by the image or some external effects. Further refinement of the theory will be discussed by considering the effects of screening, which can be one mechanism for the barrier height reduction, in addition to the widely known negative affinity of diamond like carbon systems. A comparison with experimental data from carbon field emitters shows that the enhanced current found in this paper may provide an explanation for strong field emission observed recently in carbon based samples.

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“…Similar to previous studies, 35,36,38 we apply the 1D Poisson equation and the depletion approximation for / s (x)…”

Section: Contact Resistivities Of Metal-insulator-semiconductor Contamentioning

confidence: 99%

“…In this case, most of the carrier tunneling occurs close to the top of / s (x) where the barrier is thin enough for carriers to tunnel through. For TFE, same as Stratton 38 and Padovani, 35 E RM is numerically calculated following the criterion c m kT ¼ 1 and (2d), where c m is the coefficient of the quadratic term in the Taylor series of ln P(E x ).…”

Section: Contact Resistivities Of Metal-insulator-semiconductor Contamentioning

confidence: 99%

Contact resistivities of metal-insulator-semiconductor contacts and metal-semiconductor contacts

Schaekers

Barla

Horiguchi

et al. 2016

Applied Physics Letters

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Applying simulations and experiments, this paper systematically compares contact resistivities (ρc) of metal-insulator-semiconductor (MIS) contacts and metal-semiconductor (MS) contacts with various semiconductor doping concentrations (Nd). Compared with the MS contacts, the MIS contacts with the low Schottky barrier height are more beneficial for ρc on semiconductors with low Nd, but this benefit diminishes gradually when Nd increases. With high Nd, we find that even an “ideal” MIS contact with optimized parameters cannot outperform the MS contact. As a result, the MIS contacts mainly apply to devices that use relatively low doped semiconductors, while we need to focus on the MS contacts to meet the sub-1 × 10−8 Ω cm2 ρc requirement for future Complementary Metal-Oxide-Semiconductor (CMOS) technology.

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Theory of Field Emission from Semiconductors

Cited by 252 publications

References 23 publications

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Dynamical resonance tunnelling—a theory of giant emission from carbon field emitters

Contact resistivities of metal-insulator-semiconductor contacts and metal-semiconductor contacts

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