Limits...
Electrical Double Layer Capacitance in a Graphene-embedded Al2O3 Gate Dielectric.

Ki Min B, Kim SK, Jun Kim S, Ho Kim S, Kang MA, Park CY, Song W, Myung S, Lim J, An KS - Sci Rep (2015)

Bottom Line: Graphene heterostructures are of considerable interest as a new class of electronic devices with exceptional performance in a broad range of applications has been realized.In this system, the enhanced capacitance of the hybrid structure can be understood by the formation of a space charge layer at the graphene/Al2O3 interface.The electrical properties of the interface can be further explained by the electrical double layer (EDL) model dominated by the diffuse layer.

View Article: PubMed Central - PubMed

Affiliation: Thin Film Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), Yuseong P. O. Box 107, Daejeon 305-600, Republic of Korea.

ABSTRACT
Graphene heterostructures are of considerable interest as a new class of electronic devices with exceptional performance in a broad range of applications has been realized. Here, we propose a graphene-embedded Al2O3 gate dielectric with a relatively high dielectric constant of 15.5, which is about 2 times that of Al2O3, having a low leakage current with insertion of tri-layer graphene. In this system, the enhanced capacitance of the hybrid structure can be understood by the formation of a space charge layer at the graphene/Al2O3 interface. The electrical properties of the interface can be further explained by the electrical double layer (EDL) model dominated by the diffuse layer.

No MeSH data available.


Related in: MedlinePlus

Gate potential dependence of capacitance.(a) Normalized capacitance as a function of gate voltage at 1 kHz frequency for the Al2O3 and graphene-embedded capacitors. (b) Diffuse layer capacitance as a function of upper Al2O3 thickness and fitting plot from the Gouy-Chapman EDL model (red line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4632157&req=5

f3: Gate potential dependence of capacitance.(a) Normalized capacitance as a function of gate voltage at 1 kHz frequency for the Al2O3 and graphene-embedded capacitors. (b) Diffuse layer capacitance as a function of upper Al2O3 thickness and fitting plot from the Gouy-Chapman EDL model (red line).

Mentions: In order to analyze the interface in more detail, we measured the change in capacitance with respect to applied gate potential (Fig. 3a). As depicted in Fig. 2a, a set of EDLs consists of a Stern layer and a diffuse layer lined up in a series arrangement. Hence, the apparent capacitance should be limited by the layer that has lower capacitance than the others. Since, for an insulating material such as Al2O3, charge carrier concentration is rather diffuse, the capacitance from the diffuse layer is expected to be limiting. Figure 3a shows the normalized capacitance as a function of gate voltage at a frequency of 1 kHz for an Al2O3 capacitor and a graphene-embedded capacitor. A frequency of 1 kHz was adopted for this measurement because we expect to see the EDL behavior only at a frequency lower than 10 kHz. We observed gate voltage-independent behavior in capacitance for the Al2O3 capacitor without graphene, which is similar to the graphene-embedded capacitor at frequencies of 100 kHz and higher (Supplementary Fig. S3). However, the capacitance of the graphene-embedded capacitor is strongly dependent on gate potential at frequencies lower than 10 kHz. These results clearly suggest that improvement of capacitance occurred due to the formation of the diffuse layer at the interface between graphene and Al2O3. The amount of charges at the interface increases with increasing the gate potential, and the diffuse layer capacitance also increases. The effect of the potential of diffuse layer capacitance in the EDL can be expressed by the Gouy-Chapman model, which is given by28


Electrical Double Layer Capacitance in a Graphene-embedded Al2O3 Gate Dielectric.

Ki Min B, Kim SK, Jun Kim S, Ho Kim S, Kang MA, Park CY, Song W, Myung S, Lim J, An KS - Sci Rep (2015)

Gate potential dependence of capacitance.(a) Normalized capacitance as a function of gate voltage at 1 kHz frequency for the Al2O3 and graphene-embedded capacitors. (b) Diffuse layer capacitance as a function of upper Al2O3 thickness and fitting plot from the Gouy-Chapman EDL model (red line).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4632157&req=5

f3: Gate potential dependence of capacitance.(a) Normalized capacitance as a function of gate voltage at 1 kHz frequency for the Al2O3 and graphene-embedded capacitors. (b) Diffuse layer capacitance as a function of upper Al2O3 thickness and fitting plot from the Gouy-Chapman EDL model (red line).
Mentions: In order to analyze the interface in more detail, we measured the change in capacitance with respect to applied gate potential (Fig. 3a). As depicted in Fig. 2a, a set of EDLs consists of a Stern layer and a diffuse layer lined up in a series arrangement. Hence, the apparent capacitance should be limited by the layer that has lower capacitance than the others. Since, for an insulating material such as Al2O3, charge carrier concentration is rather diffuse, the capacitance from the diffuse layer is expected to be limiting. Figure 3a shows the normalized capacitance as a function of gate voltage at a frequency of 1 kHz for an Al2O3 capacitor and a graphene-embedded capacitor. A frequency of 1 kHz was adopted for this measurement because we expect to see the EDL behavior only at a frequency lower than 10 kHz. We observed gate voltage-independent behavior in capacitance for the Al2O3 capacitor without graphene, which is similar to the graphene-embedded capacitor at frequencies of 100 kHz and higher (Supplementary Fig. S3). However, the capacitance of the graphene-embedded capacitor is strongly dependent on gate potential at frequencies lower than 10 kHz. These results clearly suggest that improvement of capacitance occurred due to the formation of the diffuse layer at the interface between graphene and Al2O3. The amount of charges at the interface increases with increasing the gate potential, and the diffuse layer capacitance also increases. The effect of the potential of diffuse layer capacitance in the EDL can be expressed by the Gouy-Chapman model, which is given by28

Bottom Line: Graphene heterostructures are of considerable interest as a new class of electronic devices with exceptional performance in a broad range of applications has been realized.In this system, the enhanced capacitance of the hybrid structure can be understood by the formation of a space charge layer at the graphene/Al2O3 interface.The electrical properties of the interface can be further explained by the electrical double layer (EDL) model dominated by the diffuse layer.

View Article: PubMed Central - PubMed

Affiliation: Thin Film Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), Yuseong P. O. Box 107, Daejeon 305-600, Republic of Korea.

ABSTRACT
Graphene heterostructures are of considerable interest as a new class of electronic devices with exceptional performance in a broad range of applications has been realized. Here, we propose a graphene-embedded Al2O3 gate dielectric with a relatively high dielectric constant of 15.5, which is about 2 times that of Al2O3, having a low leakage current with insertion of tri-layer graphene. In this system, the enhanced capacitance of the hybrid structure can be understood by the formation of a space charge layer at the graphene/Al2O3 interface. The electrical properties of the interface can be further explained by the electrical double layer (EDL) model dominated by the diffuse layer.

No MeSH data available.


Related in: MedlinePlus