title: Insights into the interfacial properties of low-voltage CuPc field-effect transistor.
abstract: The interfacial transport properties and density of states (DOS) of CuPc near the dielectric surface in an operating organic field-effect transistor (OFET) are investigated using Kelvin probe force microscopy. We find that the carrier mobility of CuPc on high-k Al2Oy/TiOx (ATO) dielectrics under a channel electrical field of 4.3 × 10(2) V/cm reaches 20 times as large as that of CuPc on SiO2. The DOS of the highest occupied molecular orbital (HOMO) of CuPc on the ATO substrate has a Gaussian width of 0.33 ± 0.02 eV, and the traps DOS in the gap of CuPc on the ATO substrate is as small as 7 × 10(17) cm(-3). A gap state near the HOMO edge is observed and assigned to the doping level of oxygen. The measured HOMO DOS of CuPc on SiO2 decreases abruptly near E(V(GS) = V(T)), and the pinning of DOS is observed, suggesting a higher trap DOS of 10(19)-10(20) cm(-3) at the interface. The relationships between DOS and the structural, chemical, as well as electrical properties at the interface are discussed. The superior performance of CuPc/ATO OFET is attributed to the low trap DOS and doping effect.
authors: Siyuan Laboratory, Department of Physics, Jinan University, Guangzhou, Guangdong 510632, People's Republic of China.
authors: Yaorong
authors: Y
authors: Su
authors: Ming
authors: M
authors: Ouyang
authors: Pengyi
authors: P
authors: Liu
authors: Zhi
authors: Z
authors: Luo
authors: Weiguang
authors: W
authors: Xie
authors: Jianbin
authors: J
authors: Xu