Interface-Charge-Coupled Polarization Response of Pt-BaTiO3-ZnO-Pt Heterojunctions: A Physical Model Approach
Interface-Charge-Coupled Polarization Response
of Pt-BaTiO3-ZnO-Pt Heterojunctions: A Physical Model
Approach
复制标题
Pt-BaTiO3-ZnO-Pt 异质结的界面电荷耦合极化响应：物理模型方法
DOI：
10.1007/s11664-008-0461-0
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发表时间：
2008
影响因子：
2.1
通讯作者：
M. Schubert
中科院分区：
文献类型：
--
作者：
V. M. Voora;T. Hofmann;M. Brandt;M. Lorenz;M. Grundmann;N. Ashkenov;M. Schubert
由纤锌矿结构（压电）ZnO和钙钛矿结构（铁电）BaTiO 3组成的异质结是非常有趣的，因为先前观察到的离子晶格极化耦合在它们的界面处。我们报告电Sawyer-Tower极化滞后测量和分析的ZnO-BaTiO 3异质结构与Pt的前，后接触沉积在（001）硅衬底上的脉冲激光沉积。ZnO层为n型（Nc = 5.5 × 1016 cm-3），BaTiO 3（BTO）层为高电阻。我们观察到一个强大的不对称的铁电滞后，我们归因于一个整流耗尽层之间的ZnO和钛酸钡层的形成。纤锌矿结构和钙钛矿结构界面极化之间的耦合影响耗尽层的形成。我们开发了一个物理模型的电索耶塔测量。我们的模型包括ZnO层内的耗尽层形成的影响，ZnO和BaTiO 3层之间的界面电荷耦合，和BTO内的场依赖铁电极化。我们得到了一个很好的协议之间的模型生成的数据和我们的实验。我们确定了耗尽层打开或关闭的正向和反向电压。这些电压是不对称的，揭示了ZnO的自发压电（不可切换）界面电荷的影响，我们从这里的分析中确定为Psz = −4.1 μC/cm 2。
Heterojunctions composed of wurtzite-structure (piezoelectric) ZnO and perovskite-structure (ferroelectric) BaTiO3 are very interesting because of the previously observed ionic lattice polarization coupling at their interfaces. We report electric Sawyer-Tower polarization hysteresis measurements and analysis of a ZnO-BaTiO3 heterostructure with Pt front and back contacts deposited by pulsed laser deposition onto a (001) silicon substrate. The ZnO layer is n-type (Nc = 5.5 × 1016 cm−3), and the BaTiO3 (BTO) layer is highly resistive. We observe a strong asymmetric ferroelectric hysteresis, which we attribute to a rectifying depletion layer formation between the ZnO and BaTiO3 layers. The coupling between the wurtzite-structure and perovskite-structure interface polarization influences the depletion layer formation. We develop a physical model for the electric Sawyer-Tower measurements. Our model includes the effects of the depletion layer formation inside the ZnO layer, the interface charge coupling between the ZnO and BaTiO3 layers, and the field-dependent ferroelectric polarization inside the BTO. We obtain a very good agreement between our model-generated data and our experiment. We identify voltages in forward and reverse direction at which the depletion layer opens or closes. These voltages are asymmetric, and reveal the effect of the spontaneous piezoelectric (nonswitchable) interface charge of ZnO, which we determine from our analysis here as Psz = −4.1 μC/cm2.