Piezoresistive granular metal thin films of platinum–boron nitride and platinum–alumina at higher strain levels
Piezoresistive granular metal thin films of platinum–boron nitride and platinum–alumina at higher strain levels
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DOI：
10.1063/1.5054972
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发表时间：
2018-12
影响因子：
3.2
通讯作者：
S. Schwebke;S. Winter;M. Koch;G. Schultes
中科院分区：
文献类型：
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作者：
S. Schwebke;S. Winter;M. Koch;G. Schultes
颗粒状金属薄膜的应变敏感性比连续金属薄膜大得多。高应变实验有助于揭示其压阻机制。我们将氮化硼中的铂纳米颗粒薄膜 (Pt:BN) 以及氧化铝中的铂颗粒薄膜 (Pt:Al 2O 3) 沉积在聚酰亚胺箔上作为应变计。在 0.1% 的低应变下，薄膜表现出增强的应变系数，Pt:BN 的 k = 23，Pt:Al 2O 3 的 k = 6。对于 1.5% 的更高应变，Pt:BN 显示出可重复的线性电阻-应变曲线。相比之下，Pt:Al 2O 3 表现出异常现象：电阻-应变曲线高度非线性，在达到饱和之前斜率不断增加。微分应变系数与应变的关系从 9 增加到 9500，并且返回曲线显示出较大的滞后。通过扫描电子显微镜比较未应变和原位应变薄膜，Pt:BN 没有显示任何变化，而在 Pt:Al 2O 3 中，出现了大裂纹。相对较软的BN比硬而脆的Al 2O 3 更不容易产生裂纹。因此，Pt:BN中的应变系数仍然可以归因于电子隧道机制，而Pt:Al 2O 3 则主要受裂纹的影响。提出了一个模型，我们认为这些裂纹的可重复打开和闭合导致高应变下电阻的巨大增加。颗粒金属薄膜的应变敏感性比连续金属薄膜大得多。高应变实验有助于揭示其压阻机制。我们将氮化硼中的铂纳米颗粒薄膜 (Pt:BN) 以及氧化铝中的铂颗粒薄膜 (Pt:Al 2O 3) 沉积在聚酰亚胺箔上作为应变计。在 0.1% 的低应变下，薄膜表现出增强的应变系数，Pt:BN 的 k = 23，Pt:Al 2O 3 的 k = 6。对于 1.5% 的更高应变，Pt:BN 显示出可重复的线性电阻-应变曲线。相比之下，Pt:Al 2O 3 表现出异常现象：电阻-应变曲线高度非线性，在达到饱和之前斜率不断增加。微分应变系数与应变的关系从 9 增加到 9500，并且返回曲线显示出较大的滞后。通过扫描电子显微镜比较未应变和原位应变薄膜，Pt:BN 没有显示任何变化，而在 Pt:Al 2O 3 中，出现了大裂纹。相对较软的BN不太容易...
Granular metal thin films have a strain sensitivity much larger than continuous metal films. Experiments at high strain can help reveal their piezoresistive mechanisms. We deposit films of platinum nanoparticles in boron nitride (Pt:BN) as well as platinum particles in aluminum oxide (Pt:Al 2O 3) on polyimide foil as strain gauges. Under low strain of 0.1%, the films exhibit enhanced gauge factors, k = 23 for Pt:BN and k = 6 for Pt:Al 2O 3. Toward higher strain of 1.5%, Pt:BN shows reproducible and linear resistance-strain curves. In contrast, Pt:Al 2O 3 exhibits anomalies: The resistance-strain curves are highly nonlinear with an increasing slope before reaching saturation. The differential gauge factor versus strain increases from 9 to 9500, and the return curve shows large hysteresis. With scanning electron microscopy unstrained and in situ strained films are compared, Pt:BN shows no changes, whereas in Pt:Al 2O 3, large cracks develop. The relatively soft BN is less prone to cracks than the hard and brittle Al 2O 3. Hence, the gauge factor in Pt:BN can still be attributed to an electron tunneling mechanism, whereas Pt:Al 2O 3 becomes dominated by the influence of cracks. A model is presented, and we argue that the reproducible opening and closing of these cracks leads to the gigantic resistance increases at high strain.Granular metal thin films have a strain sensitivity much larger than continuous metal films. Experiments at high strain can help reveal their piezoresistive mechanisms. We deposit films of platinum nanoparticles in boron nitride (Pt:BN) as well as platinum particles in aluminum oxide (Pt:Al 2O 3) on polyimide foil as strain gauges. Under low strain of 0.1%, the films exhibit enhanced gauge factors, k = 23 for Pt:BN and k = 6 for Pt:Al 2O 3. Toward higher strain of 1.5%, Pt:BN shows reproducible and linear resistance-strain curves. In contrast, Pt:Al 2O 3 exhibits anomalies: The resistance-strain curves are highly nonlinear with an increasing slope before reaching saturation. The differential gauge factor versus strain increases from 9 to 9500, and the return curve shows large hysteresis. With scanning electron microscopy unstrained and in situ strained films are compared, Pt:BN shows no changes, whereas in Pt:Al 2O 3, large cracks develop. The relatively soft BN is less prone t...