Potentiometry on pentacene OFETs: Charge carrier mobilities and injection barriers in bottom and top contact configurations
Potentiometry on pentacene OFETs: Charge carrier mobilities and injection barriers in bottom and top contact configurations
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并五苯 OFET 的电位测定：底部和顶部接触配置中的载流子迁移率和注入势垒
DOI：
10.1002/pssa.200723415
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
D. Zahn
中科院分区：
文献类型：
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作者：
R. Scholz;D. Lehmann;A. Müller;F. Müller;D. Zahn
结合电探针、电位测定法和电荷瞬态光谱（QTS）等实验技术，我们提出了如何量化五苯ofet中触点处的电位下降、通道区域的迁移率和深阱态密度的概念。对于未纯化的并五苯在预图型金底触点上生长的ofet，电位测定法和二维器件模拟的比较确定了源触点处的注入势垒为0.73 eV，并在并五苯通道内的空穴迁移率为0.014 cm2 V-1 s-1。温度相关的QTS数据显示，空穴输运带的陷阱能级约为125 meV，表明无意掺杂剂的密度相对较高，因此大多数载流子的背景密度较高。在从纯化的并五苯生长到SiO2栅极电介质上的ofet中，在不破坏真空的情况下，Au顶部触点蒸发到并五苯通道上，电位测定显示金属功函数与有机层中的空穴输运水平几乎完美地对齐。这些样品中较低的深阱密度将空穴迁移率提高到0.1-0.2 cm2 V-1 s-1。用正十八环三氯硅烷（OTS）对栅极氧化物进行化学处理，可以进一步提高空穴迁移率和器件性能。（©2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim）
In a combination of experimental techniques including electrical probes, potentiometry, and charge transient spectroscopy (QTS), we develop concepts how to quantify the potential drops at the contacts, the mobility in the channel region, and the density of states of deep traps in pentacene OFETs. For OFETs grown from unpurified pentacene on pre‐patterned Au bottom contacts, a comparison between potentiometry and two‐dimensional device simulations determines an injection barrier of 0.73 eV at the source contact and a hole mobility of 0.014 cm2 V–1 s–1 in the pentacene channel. Temperature‐dependent QTS data reveal a trap level at about 125 meV from the hole transport band, indicating a relatively high density of unintentional dopants and therefore a high background density of majority charge carriers. In OFETs grown from purified pentacene onto a SiO2 gate dielectric and Au top contacts evaporated onto the pentacene channel without breaking the vacuum, potentiometry reveals a nearly perfect alignment of the metal work function with the hole transport level in the organic layer. The much lower density of deep traps in these samples raises the hole mobility to the range 0.1–0.2 cm2 V–1 s–1. A further improvement of the hole mobility and the resulting device performance can be achieved by a chemical treatment of the gate oxide with n‐octadecytrichlorosilane (OTS). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)