Energy spectrum of near-edge holes and conduction mechanisms in Cu2ZnSiSe4 single crystals
Energy spectrum of near-edge holes and conduction mechanisms in Cu2ZnSiSe4 single crystals
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DOI：
10.1016/j.jallcom.2013.06.156
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发表时间：
2013-12
影响因子：
6.2
通讯作者：
K. Lisunov;M. Guc;S. Levcenko;D. Dumcenco;Ying-Sheng Huang;G. Gurieva;S. Schorr;E. Arushanov
中科院分区：
文献类型：
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作者：
K. Lisunov;M. Guc;S. Levcenko;D. Dumcenco;Ying-Sheng Huang;G. Gurieva;S. Schorr;E. Arushanov
通过对cu2znsise4单晶的电阻率ρ(T)的研究，提出了cu2znsise4价带边缘附近空穴能谱的模型。在~ 100 ~ 200 K温度区间建立了Mott变范围跳变（VRH）电导率机制，而在~ 200 ~ 300 K温度区间，电导率由空穴对重叠受体带和价带联合能谱迁移率边缘的热激发决定。确定了局域化空穴的参数和价带边缘态密度的细节，包括相对受体浓度N/Nc≈0.41-0.49（其中enc≈7 × 1018cm−3为金属-绝缘体跃迁的临界浓度）、相对局域化半径/aB≈1.7-2.1（其中aB≈13.1 Å为玻尔半径）、受体带半宽度W≈95-106 meV，以价带顶部上方能量ye0≈59 meV为中心。局域态的平均密度（DOS）为gav ~ （1.4 ~ 1.8） × 1016meV−1cm−3，费米能级的DOS为g(μ)≈(4.1 ~ 5.4)× 1015meV−1cm−3。
A model of the energy spectrum of holes near the edge of the valence band of Cu2ZnSiSe4is proposed from investigations of the resistivity,ρ(T), in Cu2ZnSiSe4single crystals. The Mott variable-range hopping (VRH) conductivity mechanism is established in the temperature interval of ∼100–200 K, whereas between ∼200 and 300 K, the conductivity is determined by thermal excitations of holes to the mobility edge of the joint energy spectrum of the overlapped acceptor and valence bands. Parameters of the localized holes and details of the density of states near the edge of the valence band are determined, including the relative acceptor concentration,N/Nc≈ 0.41–0.49 (whereNc≈ 7 × 1018cm−3is the critical concentration of the metal–insulator transition), the relative localization radiusa/aB≈ 1.7–2.1 (whereaB≈ 13.1 Å is the Bohr radius), the semi-width of the acceptor band,W≈ 95–106 meV, centered at the energyE0≈ 59 meV above the top of the valence band, the average density of the localized states (DOS),gav∼ (1.4–1.8) × 1016meV−1cm−3and the DOS at the Fermi level,g(μ) ≈ (4.1–5.4) × 1015meV−1cm−3.