High-Density Carrier Accumulation in ZnO Field-Effect Transistors Gated by Electric Double Layers of Ionic Liquids
High-Density Carrier Accumulation in ZnO Field-Effect Transistors Gated by Electric Double Layers of Ionic Liquids
复制标题
DOI：
10.1002/adfm.200801633
复制
发表时间：
2009-04-09
影响因子：
19
通讯作者：
Iwasa, Yoshihiro
中科院分区：
文献类型：
--
作者：
Yuan, Hongtao;Shimotani, Hidekazu;Iwasa, Yoshihiro
最近，通过将载流子调整到高密度水平(1 x 10(14) cm(-2))，实现了绝缘体中的电场诱导超导性。提高半导体场效应晶体管中电子态静电调谐的最大载流子密度是一个热点问题，但也是一个巨大的挑战。本文报道了在离子液体双电层门控的ZnO场效应晶体管中，特别是在低温下的超高密度载流子积累。这种晶体管被称为双电层晶体管（EDLT），被发现以快速、可逆和可重复的方式表现出非常高的跨导性和超高载流子密度。根据霍尔效应测量，edlt的室温电容可达34 μ F cm(-2)，主要负责在很宽的范围内调制载流子密度。重要的是，具有过冷特性的IL介电介质即使在低温下也具有电荷积累能力，在220 K时达到8 x 10(14) cm（-2）的超高载流子密度，在1.8 K时保持5.5 x 10(14) cm（-2）的密度。这种高载流子密度不仅在实际器件应用中具有重要意义，而且在基础研究中也具有重要意义。例如，在寻找新的电子现象，如氧化物系统中的超导性。
Very recently, electric-field-induced superconductivity in an insulator was realized by tuning charge carrier to a high density level (1 x 10(14) cm(-2)). To increase the maximum attainable carrier density for electrostatic tuning of electronic states in semiconductor field-effect transistors is a hot issue but a big challenge. Here, ultrahigh density carrier accumulation is reported, in particular at low temperature, in a ZnO field-effect transistor gated by electric double layers of ionic liquid (IL). This transistor, called an electric double layer transistor (EDLT), is found to exhibit very high transconductance and an ultrahigh carrier density in a fast, reversible, and reproducible manner. The room temperature capacitance of EDLTs is found to be as large as 34 mu F cm(-2), deduced from Hall-effect measurements, and is mainly responsible for the carrier density modulation in a very wide range. Importantly, the IL dielectric, with a supercooling property, is found to have charge-accumulation capability even at low temperatures, reaching an ultrahigh carrier density of 8 x 10(14) cm(-2) at 220 K and maintaining a density of 5.5 x 10(14) cm(-2) at 1.8 K. This high carrier density of EDLTs is of great importance not only in practical device applications but also in fundamental research; for example, in the search for novel electronic phenomena, such as superconductivity, in oxide systems.