Dielectric dynamics of the polycrystalline Ba0.5Sr0.5TiO3 thin films
Dielectric dynamics of the polycrystalline Ba0.5Sr0.5TiO3 thin films
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DOI：
10.1209/0295-5075/114/47009
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发表时间：
2016-05
期刊：
影响因子：
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通讯作者：
Tanja Pečnik;A. Eršte;Aleksander Matavž;V. Bobnar;M. Ivanov;J. Banys;Feng Xiang;Hong Wang;B. Malič;S. Glinšek
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文献类型：
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作者：
Tanja Pečnik;A. Eršte;Aleksander Matavž;V. Bobnar;M. Ivanov;J. Banys;Feng Xiang;Hong Wang;B. Malič;S. Glinšek
采用化学溶液沉积法（CSD）在900 °C下在氧化铝衬底上制备了厚度为90 ~ 600 nm的Ba0.5Sr0.5TiO3多晶薄膜，并对其面内特性进行了介电谱研究。5 kHz的介电常数ε′表现出非单调的厚度依赖性，对于310 nm厚的薄膜，其晶粒尺寸为1275 nm，在室温下达到1230。其15 GHz值和损耗分别为1105和0.05。在5 kHz的介电常数最大值Tmax的温度随着厚度从277到250 K的170和600 nm厚的膜，分别增加，这已被链接到残余双轴应力。当温度高于T_（max）~ 1050 K时，所有薄膜的介电常数ε′-电场EDC特性都出现了滞后现象。频率色散，其中介电常数随频率的增加而降低是目前低于Tmax在膜厚大于90 nm。最薄的膜的高介电常数值，这是在晶粒尺寸低于75 nm的（Ba，Sr）TiO 3膜中报道的最高的介电常数值，是优化的CSD处理条件的直接证明。
Polycrystalline Ba0.5Sr0.5TiO3 films, with thicknesses between 90 and 600 nm, were prepared on alumina substrates at 900 °C by chemical solution deposition (CSD) and a dielectric spectroscopy investigation of the in-plane properties was performed. The 5-kHz permittivity ε′ shows a non-monotonic thickness dependence, reaching 1230 at room temperature for the 310-nm-thick film, whose grain size is ∼75 nm. Its 15-GHz-value and losses are 1105 and 0.05, respectively. The temperature of the permittivity maximum Tmax at 5 kHz decreases with increasing thickness from 277 to 250 K for the 170- and 600-nm-thick films, respectively, which has been linked to the residual biaxial stress. A hysteresis is observed in the permittivity ε′-electric field EDC characteristics in all the films up to ∼50 K above Tmax. Frequency dispersion in which permittivity decreases with increasing frequency is present below Tmax in films thicker than 90 nm. The high permittivity values of the thinnest films, which are among the highest reported in the (Ba,Sr)TiO3 films with grain sizes below 75 nm, are a direct proof of the optimized CSD processing conditions.