Substrate-induced modulation of metal-insulator transition and low-temperature charge transport in radio frequency sputtered VO2 films

IF 2 4区材料科学 Q3 MATERIALS SCIENCE, COATINGS & FILMS

Thin Solid Films Pub Date : 2025-08-16 DOI:10.1016/j.tsf.2025.140773

Akash Kumar Singh , Suman Kumari , H.K. Singh , P.K. Siwach

{"title":"Substrate-induced modulation of metal-insulator transition and low-temperature charge transport in radio frequency sputtered VO2 films","authors":"Akash Kumar Singh , Suman Kumari , H.K. Singh , P.K. Siwach","doi":"10.1016/j.tsf.2025.140773","DOIUrl":null,"url":null,"abstract":"<div><div>In this study, we investigate the influence of substrate type on the phase transition behavior and charge transport characteristics of polycrystalline VO2 films grown by Radio Frequency (RF) magnetron sputtering of a V2O5 target in pure argon ambient at ∼700 °C. The films were deposited on five single-crystal substrates namely, Yttria Stabilized Zirconia [YSZ (001)], Lanthanum Aluminate [LAO (100)], Magnesium Oxide [MgO (100)], c-plane Sapphire [ALO (0001)], and Zinc Oxide [ZnO (0001)]. Structural and Raman analysis confirmed the dominance of the VO2 phase with minor secondary V-O phases. Surface morphology revealed substrate-dependent uniformity and grain structure. Films on YSZ (001), LAO (100), and MgO (100) exhibited a sharp and reversible Insulator-Metal/Metal-Insulator transition (IMT/MIT) around ∼(339–341 K/66–68 °C), with narrow Thermal hysteresis (TH) varies from ∼(4–8 K) and a two-order resistivity change. In contrast, films on ALO (0001) and ZnO (0001) showed broader transitions, lower transition temperatures (TIM/TMI ∼331–337 K/58–64 °C), and reduced resistivity change, particularly on ZnO (0001), which displayed a single-order transition with a larger hysteresis (∼10 K). The Temperature Coefficient of Resistance/Resistivity (TCR) showed trends consistent with resistivity behavior, reaching values as high as −98 % K-1 near the IMT/MIT. Activation energy (EA) in the insulating phase varied significantly with substrate, from ∼0.221 eV (MgO) to ∼0.395 eV (ZnO), and low-temperature conduction (300 K ≤ T ≤ 4.2 K) revealed a crossover from Efros–Shklovskii Variable Range Hopping (ES-VRH) on symmetric substrates [YSZ (001), LAO (100), MgO (100)] to Nearest-Neighbor Hopping (NN<img>H) on ALO (0001) and ZnO (0001). These results underline the critical role of substrate symmetry and orientation in tailoring the phase transition dynamics and transport mechanisms in VO2 films, providing useful guidelines for substrate-engineered VO2-based device applications.</div></div>","PeriodicalId":23182,"journal":{"name":"Thin Solid Films","volume":"826 ","pages":"Article 140773"},"PeriodicalIF":2.0000,"publicationDate":"2025-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Thin Solid Films","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0040609025001725","RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATERIALS SCIENCE, COATINGS & FILMS","Score":null,"Total":0}

引用次数: 0

Abstract

In this study, we investigate the influence of substrate type on the phase transition behavior and charge transport characteristics of polycrystalline VO₂ films grown by Radio Frequency (RF) magnetron sputtering of a V₂O₅ target in pure argon ambient at ∼700 °C. The films were deposited on five single-crystal substrates namely, Yttria Stabilized Zirconia [YSZ (001)], Lanthanum Aluminate [LAO (100)], Magnesium Oxide [MgO (100)], c-plane Sapphire [ALO (0001)], and Zinc Oxide [ZnO (0001)]. Structural and Raman analysis confirmed the dominance of the VO₂ phase with minor secondary V-O phases. Surface morphology revealed substrate-dependent uniformity and grain structure. Films on YSZ (001), LAO (100), and MgO (100) exhibited a sharp and reversible Insulator-Metal/Metal-Insulator transition (IMT/MIT) around ∼(339–341 K/66–68 °C), with narrow Thermal hysteresis (T_H) varies from ∼(4–8 K) and a two-order resistivity change. In contrast, films on ALO (0001) and ZnO (0001) showed broader transitions, lower transition temperatures (T_IM/T_MI ∼331–337 K/58–64 °C), and reduced resistivity change, particularly on ZnO (0001), which displayed a single-order transition with a larger hysteresis (∼10 K). The Temperature Coefficient of Resistance/Resistivity (TCR) showed trends consistent with resistivity behavior, reaching values as high as −98 % K^-1 near the IMT/MIT. Activation energy (E_A) in the insulating phase varied significantly with substrate, from ∼0.221 eV (MgO) to ∼0.395 eV (ZnO), and low-temperature conduction (300 K ≤ T ≤ 4.2 K) revealed a crossover from Efros–Shklovskii Variable Range Hopping (ES-VRH) on symmetric substrates [YSZ (001), LAO (100), MgO (100)] to Nearest-Neighbor Hopping (NNH) on ALO (0001) and ZnO (0001). These results underline the critical role of substrate symmetry and orientation in tailoring the phase transition dynamics and transport mechanisms in VO₂ films, providing useful guidelines for substrate-engineered VO₂-based device applications.

查看原文本刊更多论文

射频溅射VO2薄膜中金属-绝缘体跃迁和低温电荷输运的衬底诱导调制

在这项研究中，我们研究了衬底类型对V2O5靶材的射频磁控溅射生长的多晶VO2薄膜的相变行为和电荷输运特性的影响。薄膜被沉积在五种单晶衬底上，即钇稳定氧化锆[YSZ(001)]、铝酸镧[LAO(100)]、氧化镁[MgO(100)]、c平面蓝宝石[ALO(0001)]和氧化锌[ZnO(0001)]。结构和拉曼分析证实了VO2相的优势和次要的V-O相。表面形貌显示出与衬底相关的均匀性和晶粒结构。YSZ（001）、LAO（100）和MgO（100）上的薄膜在~ （339-341 K/ 66-68°C）附近呈现出急剧可逆的绝缘体-金属/金属-绝缘体转变（IMT/MIT），热滞后（TH）在~ (4-8 K之间变化，电阻率呈二阶变化。相比之下，在ALO（0001）和ZnO（0001）上的薄膜表现出更广泛的转变，更低的转变温度（TIM/TMI ~ 331 ~ 337 K/58 ~ 64℃），电阻率变化更小，特别是在ZnO（0001）上，表现出单级转变，迟滞较大（~ 10 K）。电阻率温度系数（TCR）表现出与电阻率行为一致的趋势，在IMT/MIT附近达到高达- 98% K-1。绝缘相的活化能（EA）随衬底变化显著，从~ 0.221 eV （MgO）到~ 0.395 eV (ZnO)，低温导通（300 K≤T≤4.2 K）显示了对称衬底上的Efros-Shklovskii可变范围跳变（ES-VRH） [YSZ (001), LAO (100), MgO(100)]与ALO（0001）和ZnO（0001）上的最近邻跳变（NNH）的交叉。这些结果强调了衬底对称和取向在调整VO2薄膜的相变动力学和输运机制方面的关键作用，为衬底工程VO2器件的应用提供了有用的指导。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Thin Solid Films 工程技术-材料科学：膜

CiteScore

4.00

自引率

4.80%

发文量

381

审稿时长

7.5 months

期刊介绍： Thin Solid Films is an international journal which serves scientists and engineers working in the fields of thin-film synthesis, characterization, and applications. The field of thin films, which can be defined as the confluence of materials science, surface science, and applied physics, has become an identifiable unified discipline of scientific endeavor.