First-principles calculation of capacitance including interfacial effects

Lee, Bora; Lee, Choong‐Ki; Han, Seungwu; Lee, Jaichan; Hwang, Cheol Seong

doi:10.1063/1.2832413

Cited by 19 publications

(18 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…22 Second, it was shown that the intrinsic dead layer with low dielectric constants exist at the metal-STO interface. [23][24][25] A similar effect is likely to occur at the LAO-STO interface. As was shown above, about 70% of electrons are confined within 3 nm from the interface, where the interfacial effects might be strong.…”

Section: ͑4͒mentioning

confidence: 85%

Density and spatial distribution of charge carriers in the intrinsicn-typeLaAlO3-SrTiO3interface

et al. 2009

Self Cite

View full text Add to dashboard Cite

In order to establish the density and spatial distribution of charge carriers intrinsic to the n-type LaAlO 3 -SrTiO 3 heterointerface, we carry out first-principles calculations on the ͑LaAlO 3 ͒ n ͑SrTiO 3 ͒ 15 slab model with n = 2 -10. As the thickness of the LaAlO 3 layer increases, the charge transfer from LaAlO 3 to SrTiO 3 converges to half an electron per two-dimensional unit cell. It is found that the electrons in the conduction band of SrTiO 3 consist of various types of interface-bound states. The mobile electrons evaluated by excluding those states tightly bound to the interface within 2 nm or having large effective masses are in good agreement with the experimental carrier densities for all LaAlO 3 thicknesses, suggesting that the loosely bound states play a major role in the transport property. A large calculation including up to ͑LaAlO 3 ͒ 5 ͑SrTiO 3 ͒ 30 shows that about 70% of electrons are confined within 3 nm from the interface, which is in good comparison with the experiments. It is found that the transferred electrons decay exponentially at short distances from the interface, but there is a crossover to an algebraically decaying region at ϳ4 nm.

show abstract

Section: ͑4͒mentioning

confidence: 85%

Density and spatial distribution of charge carriers in the intrinsicn-typeLaAlO3-SrTiO3interface

et al. 2009

Self Cite

View full text Add to dashboard Cite

show abstract

“…They also suggested another approach, which uses conventional ab initio codes such as VASP (Vienna ab initio Simulation Package) and PWscf (Plane Wave Self Consistent Field), by simulating only the Metal/Insulator in the presence of vacuum. This method was successfully implemented by Lee et al 40 and used to calculate the capacitance of Au/MgO/Au and Ni/ZrO 2 /Ni systems.…”

Section: Theoretical Results First Principles Calculations and Pmentioning

confidence: 99%

“…This exactly corresponds to a zero inverse permittivity in the metal that increases as one approach closer to the metal-insulator interface---in good agreement with the simulated profile. The static and optical dielectric constants are estimated to be 9.52 and 2.78 compared to 9.65 and 3.36 of Reference 40 .…”

mentioning

confidence: 99%

Understanding the origins of the intrinsic dead layer effect in nanocapacitors

2009

View full text Add to dashboard Cite

Thin films of high-permittivity dielectrics are considered ideal candidates for realizing high charge density nanoscale capacitors for use in next generation energy storage and nanoelectronics applications. The experimentally observed capacitance of such film nanocapacitors is, however, an order of magnitude lower than expected. This dramatic drop in capacitance is attributed to the so-called "dead layer" -a low-permittivity layer at the metal-dielectric interface in series with the high-permittivity dielectric. Recent evidence suggests that this effect is intrinsic in the sense that its emergence is evident even in "perfectly" fabricated structures. The exact nature of the intrinsic dead-layer and the reasons for its origin still remain somewhat unclear. Based on insights gained from recently published ab initio work on SrRuO 3 /SrTiO 3 /SrRuO 3 and our first principle simulations on Au/MgO/Au and Pt/MgO/Pt nanocapacitors, we construct an analytical model that isolates the contributions of various physical mechanisms to the intrinsic dead layer. In particular we argue that strain-gradients automatically arise in very thin films even in complete absence of external strain inducers and, due to flexoelectric coupling, are dominant contributors to the dead layer effect. Our theoretical results compare well with existing, as well as our own, ab initio calculations and suggest that inclusion of flexoelectricity is essential for qualitative reconciliation of atomistic results. Our results also hint at some novel remedies for mitigating the dead layer effect.

show abstract

“…To overcome this limitation, several methods have been developed in recent years for consideration of bias voltage within the KS-DFT formalism. [11][12][13][14][15][16][17][18][19][20][21] However, they have not seen widespread use due to limitations in accuracy and/or efficiency, geometric constraints, and difficulty in implementation. We discuss some of these points in more detail below.…”

Section: Introductionmentioning

confidence: 99%

Orbital-separation approach for consideration of finite electric bias within density-functional total-energy formalism

2011

Self Cite

View full text Add to dashboard Cite

We present a simple approach for the consideration of bias voltage within the Kohn-Sham formalism of density-functional theory. To be specific, the electronic charging of a metal-insulator-metal capacitor under bias voltage is considered explicitly. This is achieved by separating the Kohn-Sham orbitals around the Fermi level into anode or cathode parts and applying different Fermi levels in the determination of occupation numbers. The formal basis of the present approach is discussed in detail. We test this method against Au-vacuum-Au and Au-MgO-Au capacitors with various dielectric thicknesses. It is shown that the bulk optical and static dielectric constants can be obtained accurately. We also demonstrate that interface effects on capacitance can be investigated straightforwardly. Furthermore, we apply this method to the graphene capacitor and identify the quantum effects in the capacitance, which is well explained by the contribution of the kinetic energy of electrons to the capacitance. The present method can be readily implemented in conventional first-principles codes and provides a unified approach to evaluate capacitance of nanodevices.

show abstract

First-principles calculation of capacitance including interfacial effects

Cited by 19 publications

References 19 publications

Density and spatial distribution of charge carriers in the intrinsicn-typeLaAlO3-SrTiO3interface

Density and spatial distribution of charge carriers in the intrinsicn-typeLaAlO3-SrTiO3interface

Understanding the origins of the intrinsic dead layer effect in nanocapacitors

Orbital-separation approach for consideration of finite electric bias within density-functional total-energy formalism

Contact Info

Product

Resources

About