Charge Transfer Doping of Silicon

Rietwyk, Kevin J.; Smets, Yaou; Bashouti, Muhammad Y.; Christiansen, Silke; Schenk, Alex; Tadich, Anton; Edmonds, Mark T.; Ristein, J.; Ley, L.; Pakes, C. I.

doi:10.1103/physrevlett.112.155502

Cited by 25 publications

(32 citation statements)

References 33 publications

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“…In addition, the interface dipoles formed by the transferred electrons in the oxide and the compensating H + ions in the water layer set up a potential step Δφ C that also contributes to the lowering of work function. The potential drop Δφ C can be modeled by a parallel‐plate capacitor

Δ ϕ_{normalC} = \frac{q Q}{C_{□}}

where C □ = ε I ε 0 / d is the interface capacitance per unit area of the oxide/water interface layer with relative permittivity ε I and d is the distance between the center of gravity of the two charge populations, while q is the magnitude of the elementary charge . A distance d = 4.62 Å is used, which results from adding the length of an OH bond (1.1 Å), a hydrogen bond (1.97 Å), and half the thickness of water layer (1.55 Å).…”

Section: Resultsmentioning

confidence: 99%

“…This has just been done for Δφ C . For the connection between Q and the change in band bending, we extended the solution to the 1D Poisson equation reported by Rietwyk et al to include both bulk donor N D and acceptor N A concentrations as well. The result reads

Q = \sqrt{2 ε_{normalS} ε_{0} k T ([], N_{D} (\exp (\frac{normalΔ (E_{normalF} - E_{VBM})}{k T}) - \frac{Δ (E_{F} - E_{normalVBM})}{k T} - 1) + N_{A} (\exp (\frac{- normalΔ (E_{normalF} - E_{VBM})}{k T}) + \frac{Δ (E_{F} - E_{normalVBM})}{k T} - 1))}

Here, ε S is the relative permittivity of the oxide, k is the Boltzmann constant, and T = 298 K (room temperature).…”

Section: Resultsmentioning

confidence: 99%

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Universal Work Function of Metal Oxides Exposed to Air

Rietwyk

Keller

Ginsburg

et al. 2019

Adv Materials Inter

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Metal oxides are the cornerstone of thin‐film electronics, a multibillion dollar industry, because they possess a wide variety of optoelectronic properties, exhibit novel functionalities, and can typically be fabricated from cheap, nontoxic raw materials. However, for thin‐film electronics to achieve further market penetration, it is necessary to replace expensive vacuum‐based fabrication processes with low‐cost, large‐scale solution‐based methods. Here, the influence of exposure to air on the band energies of metal oxides is investigated, which is crucial for predicting the operation of thin‐film devices under realistic conditions. A universal reduction in the work function is observed across 18 oxides, and for a subset, n‐type doping of the surfaces is observed after they have been exposed to atmosphere for extended periods of time. These effects arise from charge transfer events with the ubiquitous water layer that forms on surfaces in air. A quantitative analysis of the changes is provided based on the electrochemical transfer doping model, and the amount of transferred charge and the equilibrium work function of oxides in air are calculated which are in agreement with the measurements.

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Δ ϕ_{normalC} = \frac{q Q}{C_{□}}

Section: Resultsmentioning

confidence: 99%

Q = \sqrt{2 ε_{normalS} ε_{0} k T ([], N_{D} (\exp (\frac{normalΔ (E_{normalF} - E_{VBM})}{k T}) - \frac{Δ (E_{F} - E_{normalVBM})}{k T} - 1) + N_{A} (\exp (\frac{- normalΔ (E_{normalF} - E_{VBM})}{k T}) + \frac{Δ (E_{F} - E_{normalVBM})}{k T} - 1))}

Here, ε S is the relative permittivity of the oxide, k is the Boltzmann constant, and T = 298 K (room temperature).…”

Section: Resultsmentioning

confidence: 99%

Universal Work Function of Metal Oxides Exposed to Air

Rietwyk

Keller

Ginsburg

et al. 2019

Adv Materials Inter

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“…h) Experimentally determined doping efficiency (data points) and the calculated probability P + of positive charge on a CoCp 2 * molecule (line) as a function of coverage. h) Reproduced with permission . Copyright 2014, American Physical Society.…”

Section: Sctd In 1d Nanostructuresmentioning

confidence: 99%

“…To this end, solid organic or inorganic molecules with appropriate band energy levels are promising candidates. It has been reported that stable p‐type SCTD in Si NWs can be achieved via surface coating with F4‐TCNQ or MoO 3 thin films, while an n‐type SCTD of Si NWs has been realized by the adsorption of organic cobaltocene (CoCp 2 *) molecules . Besides electrical characterization, the Si core‐level shift in photoelectron spectroscopy also revealed the efficient doping process induced by interfacial charge transfer.…”

Section: Sctd In 1d Nanostructuresmentioning

confidence: 99%

Surface Charge Transfer Doping of Low‐Dimensional Nanostructures toward High‐Performance Nanodevices

Zhang¹,

Shao²,

He³

et al. 2016

Advanced Materials

176

139

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Device applications of low-dimensional semiconductor nanostructures rely on the ability to rationally tune their electronic properties. However, the conventional doping method by introducing impurities into the nanostructures suffers from the low efficiency, poor reliability, and damage to the host lattices. Alternatively, surface charge transfer doping (SCTD) is emerging as a simple yet efficient technique to achieve reliable doping in a nondestructive manner, which can modulate the carrier concentration by injecting or extracting the carrier charges between the surface dopant and semiconductor due to the work-function difference. SCTD is particularly useful for low-dimensional nanostructures that possess high surface area and single-crystalline structure. The high reproducibility, as well as the high spatial selectivity, makes SCTD a promising technique to construct high-performance nanodevices based on low-dimensional nanostructures. Here, recent advances of SCTD are summarized systematically and critically, focusing on its potential applications in one- and two-dimensional nanostructures. Mechanisms as well as characterization techniques for the surface charge transfer are analyzed. We also highlight the progress in the construction of novel nanoelectronic and nano-optoelectronic devices via SCTD. Finally, the challenges and future research opportunities of the SCTD method are prospected.

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“…Knowledge of the depth profile of energetics at the interface is paramount to understanding the operation of thin film devices and two key methods for measuring this have matured. One involves a stepwise growth of a film onto a substrate with concurrent photoemission or Kelvin probe analysis performed in ultrahigh vacuum with interconnected deposition and analysis chambers and the other, is to cleave or mill and polish a complete device and measure the work function across the cross‐section using a scanning Kelvin probe force microscopy in air, or nitrogen atmosphere to minimize oxygen and humidity (if the measurement atmosphere was unstated in the paper it was presumed air). The stepwise approach using photoemission is more common and offers detailed electronic and chemical analysis with high surface sensitivity of ≈5–10 nm (laboratory based light source) but can be slow and cumbersome to perform, especially when the substrate is heated during the deposition and subsequently cooled to room‐temperature for analysis.…”

Section: Introductionmentioning

confidence: 99%

High‐Throughput Electrical Potential Depth‐Profiling in Air

Rietwyk

Keller

Majhi

et al. 2017

Adv Materials Inter

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The operation of thin-film electronic devices is dictated by the band alignment at the interfaces of the various layers. While a number of methods for measuring the depth profile of the electrical potential at interfaces have emerged, these are typically arduous to perform and involve the use of ultra-high vacuum, complicated sample preparation and/or suffer from poor resolution. Here we present a method to directly map the depth profile of the electrical potential at an interface in air by growing a sample with an intentional thickness gradient and correlating the surface potential, measured using (macroscale) scanning Kelvin probe, to the thickness at each point. Our approach is non-destructive and rapid, is ideal for large substrates and films grown with an inherent thickness gradient. It enjoys very high depth (2 nm) and energy resolution (5 meV), comparable to other methods. In this work we develop and demonstrate the method on layer.

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Charge Transfer Doping of Silicon

Cited by 25 publications

References 33 publications

Universal Work Function of Metal Oxides Exposed to Air

Universal Work Function of Metal Oxides Exposed to Air

Surface Charge Transfer Doping of Low‐Dimensional Nanostructures toward High‐Performance Nanodevices

High‐Throughput Electrical Potential Depth‐Profiling in Air

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