Characterization of graphene-silicon Schottky barrier diodes using impedance spectroscopy

Yim, Chanyoung; McEvoy, Niall; Duesberg, Georg S.

doi:10.1063/1.4829140

Cited by 87 publications

(67 citation statements)

References 32 publications

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“…Such a large discrepancy between the experimental and theoretical values of Richardson constant could be attributed to the potential fluctuations at the Schottky interface caused by the presence of low and high barrier patches [21,22]. In addition, structural defects, wrinkles of the graphene and fabrication process induced contaminations could be a main cause of Schottky barrier inhomogeneity [23][24][25][26].…”

Section: Resultsmentioning

confidence: 99%

Temperature Dependent Current Transport Mechanism in Graphene/Germanium Schottky Barrier Diode

Khurelbaatar¹,

Kil²,

Shim³

et al. 2015

JSTS:Journal of Semiconductor Technology and Science

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Abstract-We have investigated electrical properties of graphene/Ge Schottky barrier diode (SBD) fabricated on Ge film epitaxially grown on Si substrate. When decreasing temperature, barrier height decreased and ideality factor increased, implying their strong temperature dependency. From the conventional Richardson plot, Richardson constant was much less than the theoretical value for n-type Ge. Assuming Gaussian distribution of Schottky barrier height with mean Schottky barrier height and standard deviation, Richardson constant extracted from the modified Richardson plot was comparable to the theoretical value for n-type Ge. Thus, the abnormal temperature dependent Schottky behavior of graphene/Ge SBD could be associated with a considerable deviation from the ideal thermionic emission caused by Schottky barrier inhomogeneities.

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Section: Resultsmentioning

confidence: 99%

Temperature Dependent Current Transport Mechanism in Graphene/Germanium Schottky Barrier Diode

Khurelbaatar¹,

Kil²,

Shim³

et al. 2015

JSTS:Journal of Semiconductor Technology and Science

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“…Based on the GS device structure shown in Figure 2b, the impedance spectra are analyzed with an equivalent circuit model composed of distributed voltage-dependent and independent resistance (R) and capacitance (C) networks as shown in Figure 2c. [16,17] Here the GS diode is modeled as R and C (RC) networks of silver paste-graphene contact (Ag-G), graphene (G), the interfacial layer (SiO 2 ), the silicon depletion region (D) and the silicon-gold contact (Si-Au) with the wire and bulk silicon related serial resistance (R O ) and inductance (L).…”

Section: Impedance Spectroscopy Analysismentioning

confidence: 99%

“…[13][14][15] We then compare the ideality factors with those obtained from the impedance spectra. [16,17] We designed an equivalent circuit model for analysis of impedance spectra accounting for Undoubtedly graphene-silicon (GS) heterostructure devices will play significant roles as future rectifiers, potential barrier modulators, photodetectors, photovoltaic devices, biochemical sensors, and so on. However, typical GS devices suffer from unusually wide-range voltage-dependent high ideality factors (η = 1.1-33.5).…”

mentioning

confidence: 99%

Origin of Voltage‐Dependent High Ideality Factors in Graphene–Silicon Diodes

Park

Choi

2017

Adv Elect Materials

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devices, the hurdle should be overcome by identifying the origin. However, the origin of the wide-range ideality factor was not yet been fully elucidated.The ideality factor is a measure of how efficiently an applied bias is delivered to the junction of the device. The ideality factor of GS devices can be influenced by both voltage-independent serial resistance and voltage-dependent attributes such as interface state and quantum capacitance. Thus, one can expect that the ideality factor changes with applied bias voltage.First of all, when a bias voltage is applied to a GS junction, the Fermi level of 2D graphene changes significantly in contrast to typical metal-oxide-semiconductor (MOS) devices due to the far less density of states of graphene compared to that of 3D metal. As a result, the effective Schottky barrier height and the resistance of graphene change with bias voltage. This directly influences the GS device performance and the ideality factor.Second, a peculiar issue related to the GS devices is the un avoidable wet graphene transfer process on a cleaned silicon wafer. During this process, oxidation of silicon occurs naturally. As a result, the GS devices inevitably have a native interfacial oxide layer between graphene and silicon although it may be very thin. This interfacial oxide layer directly influences the performance of GS devices. Although the layer can act as a tunneling barrier, which may enhance the effective potential barrier height, this effect has often been ignored because the layer is thin enough to assume that the transport property is largely governed by the semiconductor rather than limited by the tunneling.Third, the truncated silicon surface has high density of surface states. The surface states can exist as interface states of GS devices. The interface states can be equilibrated with silicon itself or with the graphene and this depends on the thickness of the interfacial oxide layer. Due to the very thin native oxide layer, one can expect that the silicon interface state can be mostly equilibrated with graphene rather than silicon itself. But this has not been confirmed yet.In this study, first we extract the voltage-dependent ideality factors of graphene-silicon Schottky diodes from their I-V characteristics based on Schottky emission theory. [13][14][15] We then compare the ideality factors with those obtained from the impedance spectra. [16,17] We designed an equivalent circuit model for analysis of impedance spectra accounting for Undoubtedly graphene-silicon (GS) heterostructure devices will play significant roles as future rectifiers, potential barrier modulators, photodetectors, photovoltaic devices, biochemical sensors, and so on. However, typical GS devices suffer from unusually wide-range voltage-dependent high ideality factors (η = 1.1-33.5). To overcome this hurdle, the origin of this wide-range voltage-dependent ideality factor should first be identified but this has not yet been fully studied. This study focuses on identifying the origin using impedance spectroscop...

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“…These values are higher than the ideal value of n = 1-2 for homogenous ZnO p-n junctions [33,34]. Two different possible mechanisms are believed to be responsible depending upon the temperature: (i) generation recombination for T ≤ 260 K and (ii) thermionic emission from 260 K < T ≤ 300 K. However other factors that may contribute to the deviation of n from unity are current leakage effects, a lack of free-carrier concentration at low temperatures, parasitic rectifying junctions within the device and Schottky barrier inhomogeneity in the junction area [35]. Parameter H (I) can be calculated using 'n' in Eq.…”

Section: Resultsmentioning

confidence: 99%

Hysteresis-free DC conduction in zinc oxide films with a conducting polymer counter electrode

Paul

Harris

Sharma

et al. 2017

J Mater Sci: Mater Electron

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A conducting polymer, namely poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been employed as an alternative metal counter electrode to study steady state charge conduction through a spin-coated 5.2 µm thick ZnO film in a sandwich structure on a fluorine doped tin oxide coated glass substrate. The room temperature current-voltage characteristics exhibit rectifying behaviour without hysteresis as the bias voltage is cycled between ± 10V for varying voltage sweep rate from 100 to 1000 mV/s. Thermionic emission is believed to be the dominant conduction mechanism at forward bias voltage V ≤ 2.5 V whereas the space charge limited current conduction becomes effective in a higher voltage region V > 2.5 V. The barrier height (φ b ), ideality factor (n) and series resistance (R s ) are found to be strongly temperature dependent parameters showing the increase of b and simultaneous decreases of n and R s within the range of 218-298 K. The behaviour of the temperature dependent charge carrier mobility in the higher voltage region has also been discussed. The use of PEDOT:PSS is quite promising as an alternative to metal electrodes in semiconductor devices.

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Characterization of graphene-silicon Schottky barrier diodes using impedance spectroscopy

Cited by 87 publications

References 32 publications

Temperature Dependent Current Transport Mechanism in Graphene/Germanium Schottky Barrier Diode

Temperature Dependent Current Transport Mechanism in Graphene/Germanium Schottky Barrier Diode

Origin of Voltage‐Dependent High Ideality Factors in Graphene–Silicon Diodes

Hysteresis-free DC conduction in zinc oxide films with a conducting polymer counter electrode

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