Improving Operational Stability of p‐Type Field‐Effect Transistors by Charge Selective Electrodes: a General Strategy

• Published in: Advanced electronic materials Vol. 5; no. 6
• Main Authors: Zhou, Guodong, Zhou, Shuang, Zhu, Qiang, Zhao, Ni
• Format: Journal Article
• Language: English
• Published: 01.06.2019
• Subjects: bias stress stability; conjugated polymers; field‐effect transistors; graphene; quantum dots
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.201900055

Operational instability caused by unintentional electron injection is a common problem for field‐effect transistors (FETs) based on relatively narrow‐bandgap semiconductors. Typically, the electron injection is followed by electron trapping at the semiconductor/dielectric interface or sometimes in the bulk semiconductor, resulting in a modification of the built‐in field in the FETs. Such a dynamic process causes continuous threshold voltage or Dirac voltage (Vth/Dirac) shift and thus unstable device operation. A charge‐selective electrode (CSE) design is used to address these problems. The CSE is formed by inserting a molybdenum trioxide interlayer between the electrode and the semiconductor, which creates an energy barrier to block electron injection. It is shown that the CSE strategy can generally work for FETs based on three semiconductor families, namely conjugated polymer, graphene, and quantum dot, and greatly suppresses the Vth/Dirac shift, enhancing the bias stress stability as well as reducing the noise level of the FETs. The mechanism for CSE‐reduced bias stress is investigated through trap analysis. CSE is a general strategy for achieving stable and low‐noise operation of unipolar FETs. The device design concept can be applied to other device configurations. A charge‐selective electrode (CSE) blocks electron injection via an energy barrier, thus greatly suppressing electron trapping and its subsequently induced hole trapping. CSEs improve stability and reduce noise level for field‐effect transistors based on three semiconductor families; conjugated polymer, graphene, and quantum dot. It is a promising device configuration for sensing applications.