Crystal with Metal-Insulator Transition by Plasma Processing Technique and Its Application to Switching Devices

等离子体加工技术金属-绝缘体转变晶体及其在开关器件中的应用

• 批准号: 18540495
• 负责人: OKIMURA Kunio
• 金额: $ 2.31万
• 依托单位: Tokai University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18540495/
• 关键词: vanadium dioxide; ICP-assisted sputtering; epitaxial growth; metal-insulator transition; resistive change; switching phenomenon; planer structure; stoichiometry; ププラズマプロセス; ICP支援スパッタ装置

In this project, we deposited vanadium dioxide (V0_2) films on Al_2O_3 substrates with metal-insulator transition (MIT) by using inductively coupled plasma (ICP)-assisted sputtering technique. In addition, we tried to fabricate a new switching device utilizing VO_2 film with MIT.First, we found that by selecting oxygen flow rate proper value compared to flow rate of Ar gas we can deposit stoichiometric film with MIT. Films under adequate conditions revealed MIT with three orders change in resistivity at temperature around 340 K. It was shown that this MIT is caused by crystalline structural transition from monoclinic phase to tetragonal phase through XRD analyses.Next, we fabricated a device of VO_2 with two terminal metal electrodes. We observed current jump phenomena by applying voltage to this device. We call this electric field-induced metal-insulator transition. When we decreased gap length between the two electrodes, threshold voltage that can trigger the electric field-induced MIT decreased. Thus we can control resistance change in this device by changing electrodes gap length.Finally, we fabricated two kinds of planar type devices with dimensions of the electrode gap of 5 μm and the electrode of 1500 μm and 10 μm /10 μm (electrodes gap /electrode width). In these devices, we observed fast resistance change phenomena within 200 ns. Low threshold voltage of 2 V was achieved in the former device, while large resistance ratio was achieved in the latter.Switching phenomena revealed in this project offer great interests not only in applications of VO_2 based planar device to functional electronic devices such as switching and memory devices but also in discussion on physical mechanism of switching phenomenon in oxide material with strong correlation.

本课题采用电感耦合等离子体辅助溅射技术，在具有金属-绝缘体过渡（MIT）的Al_2O_3衬底上沉积了二氧化钒（V0_2）薄膜。此外，我们还尝试了利用VO_2薄膜制作一种新的开关器件。首先，我们发现通过选择合适的氧流速值与氩气的流速相比较，我们可以用MIT沉积化学计量膜。在适当的条件下，薄膜在340 K左右的温度下电阻率发生了3个数量级的变化。XRD分析表明，这是由单斜相向四方相转变引起的。接下来，我们制作了一个带有两个金属电极的VO_2器件。我们通过对该器件施加电压观察到电流跳变现象。我们称之为电场感应金属-绝缘体转变。当我们减小两个电极之间的间隙长度时，可以触发电场诱导MIT的阈值电压降低。因此，我们可以通过改变电极间隙长度来控制该器件的电阻变化。最后，我们制作了两种尺寸分别为5 μm、1500 μm和10 μm /10 μm（电极间隙/电极宽度）的平面型器件。在这些器件中，我们观察到200 ns内的快速电阻变化现象。前者器件实现了2 V的低阈值电压，后者器件实现了较大的电阻比。本课题所揭示的开关现象不仅对基于VO_2的平面器件在开关和存储器件等功能电子器件中的应用具有重要意义，而且对探讨氧化材料中开关现象的物理机制也具有很强的相关性。

项目成果

Growth of VO_2 films wtih metal-insulator transition on silicon substrates in inductively coupled plasma-assisted sputtering

电感耦合等离子体辅助溅射硅衬底上金属-绝缘体转变VO_2薄膜的生长

• 发表时间: 2007
• 期刊: Thin Solid Films Vol.515
• 作者: M.Murakami;M.M.Basko;Kunio Okimura and N.Kubo
• 通讯作者: Kunio Okimura and N.Kubo

X-ray Diffraction Study on Electric field induced Metal-Insulator Transition of Vanadium Dioxide Films on Sapphire Substrate Prepared by Reactive Sputtering

反应溅射蓝宝石衬底上二氧化钒薄膜电场诱导金属-绝缘体转变的X射线衍射研究

• 发表时间: 2006
• 作者: Ezreena;Mohamad;Yusuke Sasakawa;Yusuke Nihei;Kunio;Okimura;Jun Takayama and Kunio Okimura;Yusuke Sasakawa and Kunio Okimura
• 通讯作者: Yusuke Sasakawa and Kunio Okimura

Time-dependent Characteristics of Electric Field-Induced Metal-Insulator Transition of Planer VO_2 /Al_2O_3 Structure

平面VO_2/Al_2O_3结构电场诱导金属-绝缘体转变随时间变化的特性

• 发表时间: 2007
• 期刊: Japanese Journal of Applied Physics Vol. 46, No. 34
• 作者: Kunio;Okimura;J;Sakai
• 通讯作者: Sakai

Expitaxial Growth of Conductive Anatase TiO_2:Nb Films on SrTiO_3 Substrate by Reactive Sputtering

反应溅射法在SrTiO_3基底上外延生长导电锐钛矿TiO_2:Nb薄膜

• 发表时间: 2006
• 作者: Ezreena;Mohamad;Yusuke Sasakawa;Yusuke Nihei;Kunio;Okimura;Jun Takayama and Kunio Okimura
• 通讯作者: Jun Takayama and Kunio Okimura

Time-dependent Characteristics of Electric Field-Induced Metal-Insulator Transition of Planer VO_2/Al_2O_3 Structure

平面VO_2/Al_2O_3结构电场诱导金属-绝缘体转变随时间变化的特性

• 发表时间: 2007
• 期刊: Japanese Journal of Applied Physics Vol.46,No.34
• 作者: Y.Nihei;Y.Sasakawa and K.Okimura;Satoshi Adachi;M. Murakami and M.M.Basko;Kunio Okimura and J Sakai
• 通讯作者: Kunio Okimura and J Sakai