Piezotronics for sensors and energy technology
Piezotronics for sensors and energy technology
复制标题
DOI：
10.1117/2.1201403.005374
复制
发表时间：
2014-03
期刊：
影响因子：
--
通讯作者：
Zhong Lin Wang;Wenzhuo Wu
中科院分区：
文献类型：
--
作者：
Zhong Lin Wang;Wenzhuo Wu
开发具有可调功能和性能的电子/光电子技术的新技术对于可穿戴电子、通信、机器人、假肢和生物医学治疗等新兴应用至关重要。对于这些应用，设备和刺激（例如，来自人体）之间的主动和自适应交互是必不可少的。尽管机械刺激在与这些电子器件/光电子器件的潜在相互作用的环境中无处不在且丰富，但它们很难用传统的硅器件实现。压电效应已广泛应用于机电传感、驱动和能量收集等领域。在缺乏反演对称性的材料中，电荷极化是对机械变形的响应。传统的压电材料如Pb(ZrxTi1 x/O3 （PZT）和聚偏氟乙烯（PVDF）是绝缘的，因此不适合用于构建功能电子或光电子器件。因此，机械诱导极化对压电材料中载流子的影响一直被忽视。具有纤锌矿或闪锌矿结构的氧化锌（ZnO）、氮化镓和硫化镉等半导体材料也具有压电特性。然而，它们的压电系数相对较小，因此尚未广泛应用于压电传感器和执行器中尽管如此，压电极化与半导体特性的结合产生了新的基本现象，并具有新的器件应用，自2006年首次发现以来，人们对新兴的“压电电子学”领域的兴趣日益增加。压电效应通过机械变形调节金属半导体（M-S）势垒或pn结的载流子输运。应变诱导电荷极化是由自由载流子的重新分布和界面附近的能带结构变化引起的（见图1）。显示压电如何调制金属-半导体（M-S）接触和pn结的示意图。(a)施加压缩应变时，M-S界面附近诱导的负压电极化离子电荷增加了局部肖特基势垒高度（SBH）。(b)施加拉伸应变时，M-S界面附近产生的正压电极化离子电荷降低了局部的SBH。(c)和(d)在应变作用下，压电极化离子电荷在p-n结界面附近被诱导。英孚;m, Ef；s：金属和半导体的费米能级。n型、p型：分别以带负电荷的电子或带正电荷的空穴为载流子的半导体。
New technologies for developing electronics/optoelectronics with tunable functionalities and performance are critical to emerging applications in wearable electronics, communications, robotics, prosthetics, and biomedical treatments. For these applications, the active and adaptive interactions between devices and stimuli (e.g., from the human body) are essential. Although mechanical stimuli are ubiquitous and abundant in the environment for potential interactions with these electronics/optoelectronics,1–3 they are difficult to implement with conventional silicon devices. The piezoelectric effect has been widely used for electromechanical sensing, actuating, and energy harvesting. Charge polarization occurs in response to mechanical deformation in materials lacking inversion symmetry. Conventional piezoelectric materials such as Pb(ZrxTi1 x/O3 (PZT) and polyvinylidene fluoride (PVDF) are insulating and hence not suitable for constructing functional electronics or optoelectronics. Because of this, the effect of mechanically induced polarization on charge carriers in piezoelectric materials has long been overlooked. Semiconductor materials such as zinc oxide (ZnO), gallium nitride, and cadmium sulfide with wurtzite or zinc blende structure also possess piezoelectric properties. However, they have relatively small piezoelectric coefficients and so have not been used as extensively in piezoelectric sensors and actuators.4 Despite this, their combination of piezoelectric polarization with semiconductor properties gives rise to novel fundamental phenomena and has novel device applications, leading to increasing interest in the emerging field of ‘piezotronics’ since it was first identified in 2006.5 The piezotronic effect modulates charge carrier transport across a metal-semiconductor (M-S) barrier or p-n junction by mechanical deformation. Straininduced charge polarization results from redistributed free carriers and band structure changes near the interface (see Figure 1. Schematic energy diagram showing how piezopotential modulates the metal-semiconductor (M-S) contact and p-n junctions. (a) With compressive strain applied, the negative piezoelectric polarization ionic charges induced near the M-S interface increase the local Schottky barrier height (SBH). (b) With tensile strain applied, the positive piezoelectric polarization ionic charges induced near the M-S interface decrease the local SBH. (c) and (d) With strain applied, the piezoelectric polarization ionic charges are induced near the p-n junction interface. Ef ;m, Ef ;s: Fermi level of the metal and semiconductor, respectively. n-type, p-type: Semiconductor with negatively charged electrons or positively charged ‘holes’ as carriers, respectively.