Dielectric and electrical properties of sputter grown (Ba,Sr)TiO3 thin films
Dielectric and electrical properties of sputter grown (Ba,Sr)TiO3 thin films
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DOI：
10.1063/1.370759
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发表时间：
1999-07-01
影响因子：
3.2
通讯作者：
Kim, HJ
中科院分区：
文献类型：
--
作者：
Shin, JC;Park, J;Kim, HJ
基于全耗尽薄膜和肖特基-隧道复合导电模型，分析了射频溅射沉积的(Ba，Sr)TiO_3(BST)薄膜的介电行为，包括介电常数、电容-电压(C-V)变化和电导行为(包括电流密度-电场变化)。C-V电容值随着薄膜厚度的增加而增加的事实清楚地表明薄膜已经完全耗尽。此外，BST膜在铂电极和IrO2电极上的介电常数分别随膜厚的减小而减小和不随膜厚的减小归因于低介电常数和很小厚度的电极界面处的本征界面层。在一定电场下，较厚薄膜的漏电流密度增加是由于溅射薄膜中的高空间电荷密度引起的界面电场强度增加所致。在电场强度小于120kV/cm时，漏电流密度受肖特基传导机制(热离子发射)控制，在该场强以上，与隧道有关的机制(热离子发射)占主导地位。在不同温度和较宽的场强范围内，基于肖特基-隧道复合导电模型计算的漏电流密度与测量的电流密度符合得很好。在所有的计算中，总是考虑电场相关的介电常数。BST薄膜与电场有关的介电常数和高的缺陷或空间电荷密度使得基于经典金属/半导体接触理论的介电和导电行为的传统分析失效。因此，考虑到溅射沉积的BST薄膜的介电特性和较高的电荷密度，建立了一个更全面的理论模型。(C)1999年美国物理研究所。[S0021-8979(99)06613-X]。
The dielectric behavior containing the film thickness dependent dielectric constant, capacitance-voltage (C-V) variation, and the electrical conduction behavior containing the film thickness dependent current density-electric field variation of rf sputter deposited (Ba,Sr)TiO3 (BST) thin films are analyzed based on a fully depleted film and a combined Schottky-tunneling conduction model. The fact that the capacitance values in C-V increase with the increasing film thickness clearly indicates that the films are fully depleted. Also, the decreasing and nonvariant dielectric constants of the BST film on the Pt and IrO2 electrodes, respectively, with decreasing film thickness are attributed to the intrinsic interfacial layers at the interfaces with electrodes which have low dielectric constants and very small thicknesses. The increased leakage current density of a thicker film under a given electric field originates from the increased interfacial field strength due to the high space charge density in the sputtered film. The leakage current density under the electric field strength smaller than 120 kV/cm is controlled by the Schottky conduction mechanism (thermionic emission), and over that field strength, the tunneling related mechanism (thermionic field emission) is predominant. The calculated leakage current density on the basis of the combined Schottky-tunneling conduction model fits well to the measured current density at various temperatures and over a wide field range. For all the calculations, the electric field dependent dielectric constant is always taken into account. The electric field dependent dielectric constant and high defect or space charge density of the BST film make the conventional analysis of the dielectric and conduction behavior based on the classical metal/semiconductor contact theory invalid. Therefore, a more comprehensive formalism is developed to take into account the field dependent dielectric properties and high charge density of the sputter deposited BST films. (C) 1999 American Institute of Physics. [S0021-8979(99)06613-X].