グラフェン超グリッドにおける弾性ミニバンド伝導
Menyoung Lee1, John R Wallbank2, Patrick Gallagher1
1Department of Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305, USA.
Science (New York, N.Y.)
|October 7, 2016
まとめ
研究者は,グラフェン/六角性酸塩 (h-BN) の超網状の電子ダイナミクスを研究した. 電子が軌道を跳び回ったり サイクロトロン運動の逆転など 独特の振る舞いを観察し 将来の超網膜装置にとって 決定的な役割を果たしました
科学分野:
- 凝縮物質物理学
- 材料科学
- ナノテクノロジー
背景:
- グラフェン/六角性化物 (h-BN) ヘテロ構造のモイールパターンのような人工の格子では,単純な固体では見られないユニークな電子特性を提供します.
- これらのヘテロ構造は,高い電子移動性と異常な電子分散性を示し,静電ゲートを通じて調節可能なミニバンドエッジとサドルポイントを有する.
研究 の 目的:
- グラフェン/h-BNヘテロ構造におけるモアールミニバンド内の電子のダイナミクスを調査する.
- これらの超格子における電子輸送現象に対する温度と磁場の影響を調査する.
主な方法:
- 磁場内のローカルコンタクトの間の弾道輸送を測定した.
- 低温と高温の両方で電子ダイナミクスを分析し,異なる輸送方式を理解しました.
主要な成果:
- 低温で数百の超格子周期を横断する軌道をスキップするカスティクスを観測した.
- 連続したミニバンドのサイクロトロン回転とヴァン・ホーブ特異点近くのサイクロトロン運動の分解を記録した.
- 電子同士の衝突が 高温で焦点効果を抑制することを発見した.
結論:
- この研究は,軌道逆転と崩壊を含むモアール超網のエキゾチックな電子ダイナミクスを明らかにします.
- これらのミニバンド伝導特性を理解することは 新しい輸送行動を持つ高度な超網状デバイスの設計に不可欠です
関連する概念動画
02:35Band Theory
17.6K
When two or more atoms come together to form a molecule, their atomic orbitals combine and molecular orbitals of distinct energies result. In a solid, there are a large number of atoms, and therefore a large number of atomic orbitals that may be combined into molecular orbitals. These groups of molecular orbitals are so closely placed together to form continuous regions of energies, known as the bands.
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
17.6K
01:01Energy Bands in Solids
2.2K
Isolated atoms have discrete energy levels that are well described by the Bohr model. And, it quantifies the energy of an electron in a hydrogen atom as En. Higher quantum numbers 'n' yield less negative, closer electron energy levels.
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states...
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states...
2.2K
01:22Semiconductors
1.8K
There is variation in the electrical conductivity of materials - metals, semiconductors, and insulators that are showcased with the help of the energy band diagrams.
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
Metals such as copper (Cu), zinc (Zn), or lead (Pb) have low resistivity and feature conduction bands that are either not fully occupied or overlap with the valence band, making a bandgap non-existent. This allows electrons in the highest energy levels of the valence band to easily transition to the conduction band upon gaining...
1.8K
01:17Theory of Metallic Conduction
1.9K
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
1.9K
01:12Fermi Level Dynamics
910
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
910
02:18Network Covalent Solids
16.4K
Network covalent solids contain a three-dimensional network of covalently bonded atoms as found in the crystal structures of nonmetals like diamond, graphite, silicon, and some covalent compounds, such as silicon dioxide (sand) and silicon carbide (carborundum, the abrasive on sandpaper). Many minerals have networks of covalent bonds.
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
16.4K