ELECTRONIC PROPERTIES OF VO2 NEAR SEMICONDUCTOR-METAL TRANSITION
ELECTRONIC PROPERTIES OF VO2 NEAR SEMICONDUCTOR-METAL TRANSITION
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DOI：
10.1103/physrev.185.1022
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发表时间：
1969-01-01
期刊：
影响因子：
--
通讯作者：
GUGGENHEIM, HJ
中科院分区：
文献类型：
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作者：
BERGLUND, CN;GUGGENHEIM, HJ
用简单的单电子能带图讨论了VO2在68℃的半导体-金属转变温度附近的光学、热、磁和输运性质。特别强调了这些性质在不同样品中的变化。结果表明，所有已有的实验数据都可以用该模型定性地解释。在金属状态下，至少有两个重叠的和部分占据的带，形成了一个复杂的费米面，其特征是电导有效质量接近1，载流子迁移率在1~10cm2/V s之间。没有一致的证据表明费米能级附近有一个非常窄的高质量带。在半导体状态下，上述能带重叠可能被晶格失真移除，导致约0.6至0.7 eV的能隙。这种能隙被填充到通常为10 19到10 20 cm−3的密度，具有类似施主和受主的状态，能量分布和密度取决于样品，因此不可能获得对能隙的准确测量。与这些类施主和类受主状态相关的电荷密度通常比与带内载流子相关的电荷密度大，导致了严重补偿的半导体的电子性质特征。在VO2的半导化相中，导带有效质量和电子迁移率几乎为一。这些实验结果对于已发表的几种固体中半导体-金属跃迁理论在VO2中的应用具有一定的指导意义。
Optical, thermal, magnetic, and transport properties of V O 2 in the vicinity of the semiconductor-metal transition temperature of 68 C are discussed in terms of a simple one-electron band picture. Particular emphasis is placed on the variation in these properties from sample to sample. It is shown that all of the available experimental data can be qualitatively explained in terms of such a model. In the metallic state, there are at least two overlapping and partially occupied bands, resulting in a complex Fermi surface characterized by a conductivity effective mass near unity and carrier mobilities in the range between 1 and 10 cm 2/V sec. There is no consistent evidence of a very narrow high-mass band near the Fermi level. In the semiconductor state, it is probable that the band overlap described above is removed by the lattice distortion, resulting in an energy gap of approximately 0.6 to 0.7 eV. This energy gap is filled to a density of typically 10 19 to 10 20 cm− 3 with donorlike and acceptorlike states, the energy distribution and density depending on the sample, so that it is impossible to obtain an accurate measure of the energy gap. The charge density associated with these donorlike and acceptorlike states is normally larger than that associated with the carriers in the band, resulting in electronic properties characteristic of heavily compensated semiconductors. The conduction-band effective mass and the electron mobility are both near unity in the semiconducting phase of V O 2. Some implications of these experimental results with respect to the application to V O 2 of several of the published theories on semiconductor-metal transitions in solids are pointed out.