Graphene/GaN Schottky diodes: Stability at elevated temperatures

Tongay, Sefaattin; Lemaitre, Maxime G.; Schumann, Timo; Berke, Kara; Appleton, B. R.; Gila, B. P.; Hebard, A. F.

doi:10.1063/1.3628315

Cited by 114 publications

(82 citation statements)

References 19 publications

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“…Furthermore, the experimentally obtained  B value of 0.74 eV [33,34] was even larger than the predicted value. These inconsistent results indicate that, for the successful development of graphene integrated GaN-based semiconductor devices, the electrical characteristics and carrier transport mechanism of the graphene-GaN contact should be thoroughly investigated.…”

Section: Introductioncontrasting

confidence: 65%

“…On the one hand, thermally stable rectifying behavior was also observed for the graphene contacts formed on n-type GaN by Tongay et al [33,34], suggesting that the graphene on n-GaN be a promising candidate for the Schottky rectifiers. This finding is strange considering that the  B expected to form at the graphene/n-GaN interface is as low as ~0.4 eV due to the small work function difference between graphene and n-GaN, implying that the graphene contact to n-GaN should produce poor rectifying behavior.…”

Section: Introductionmentioning

confidence: 78%

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Graphene-GaN Schottky diodes

et al. 2014

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The electrical characteristics of graphene Schottky contacts formed on undoped GaN semiconductors were investigated. Excellent rectifying behavior with a rectification ratio of ~10 7 at ±2 V and a low reverse leakage current of 1.0 × 10 -8 A/cm 2 at -5 V were observed. The Schottky barrier heights, as determined by the thermionic emission model, Richardson plots, and barrier inhomogeneity model, were 0.90, 0.72, and 1.24 ± 0.13 eV, respectively. Despite the predicted low barrier height of ~0.4 eV at the graphene-GaN interface, the formation of excellent rectifying characteristics with much larger barrier heights is attributed to the presence of a large number of surface states (1.2 × 10 13 states/cm 2 /eV) and the internal spontaneous polarization field of GaN, resulted in a significant upward surface band bending or a bare surface barrier height as high as of 2.9 eV. Using the S parameter of 0.48 (measured from the work function dependence of Schottky barrier height) and the mean barrier height of 1.24 eV, the work function of graphene in the Au/graphene/GaN stack could be approximately estimated to be as low as 3.5 eV. The obtained results indicate that graphene is a promising candidate for use as a Schottky rectifier in GaN semiconductors with n-type conductivity.

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Section: Introductioncontrasting

confidence: 65%

Section: Introductionmentioning

confidence: 78%

Graphene-GaN Schottky diodes

et al. 2014

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“…Typically, ideality constants greater than the unity imply a number of possibilities: (1) additional charge transport processes such as thermionic field emission exist at the interface, 17 (2) the SBH is bias dependent since the graphene Fermi level is bias dependent, [17][18][19] (3) the image force lowering 16 effect is significant at the interface, and/or (4) Schottky barrier inhomogeneity is present in the junction area. 20 In accord with these possibilities we suggest that for pristine graphene/nSi, ideality constants greater than unity can be associated with the existence of charge puddles on the graphene that are unintentionally formed during the graphene processing steps and which give rise to associated Schottky barrier inhomogeneities.…”

Section: Introductionmentioning

confidence: 99%

High Efficiency Graphene Solar Cells by Chemical Doping

et al. 2012

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We demonstrate single layer graphene/ n-Si Schottky junction solar cells that under AM1.5 illumination exhibit a power conversion efficiency (PCE) of 8.6%. This performance, achieved by doping the graphene with bis(trifluoromethanesulfonyl)amide, exceeds the native (undoped) device performance by a factor of 4.5 and the best previously reported PCE in similar devices by a factor of nearly 6. Current-voltage, capacitance-voltage and external quantum efficiency measurements show the enhancement to be due to the doping induced shift in the graphene chemical potential which increases the graphene carrier density (decreasing the cell series resistance) and increases the cell's built-in potential (increasing the open circuit voltage) both of which improve the solar cell fill factor.

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“…Unusual properties of graphene promising for a variety of novel applications [23][24][25][26][27][28] have also triggered significant interest in one or several atom-thick honeycomb structures of binary compounds. Early experimental studies aiming to synthesize and characterize novel monolayer materials have revealed that graphene-like sheets of BN are also stable.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of alkali, alkaline-earth, and 3dtransition metal atoms on silicene

2013

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The adsorption characteristics of alkali, alkaline earth and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon, are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, workfunction and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na and K, adsorb to hollow site without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene metalization of silicene takes place. Trends directly related to atomic size, adsorption height, workfunction and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline earth metals on silicene are entirely different from their adsorption on graphene. The adsorption of Be, Mg and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal and semiconducting behavior. For all metal adsorbates the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

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Graphene/GaN Schottky diodes: Stability at elevated temperatures

Cited by 114 publications

References 19 publications

Graphene-GaN Schottky diodes

Graphene-GaN Schottky diodes

High Efficiency Graphene Solar Cells by Chemical Doping

Adsorption of alkali, alkaline-earth, and 3dtransition metal atoms on silicene

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