講演情報
[23p-1BB-9]Hopping conduction in Au deposited PCBM crystal
〇Dong Han1, Takashi Yamada1, Hiroshi Ohoyama1, Takuya Matsumoto1 (1.Osaka Univ.)
キーワード：
fullerene derivative、electrical conductivity、doping
Recently, Artificial Neural Network that mimics the function of the human brain is becoming popular. Nonlinear classification has been demonstrated by using system with disordered dopant atom network in silicon. [1] The nonlinearity of hopping conduction through a network of boron dopant atoms is clarified. However, nonlinear properties emerged only at low temperatures, and these devices are desired to work at room temperature for future applications. An organic molecular system with an appropriate dopant must become one of the possible candidates as a nonlinear network system working at room temperature. Here, we propose PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) /Au molecule system as such system.
We found that small amount of Au deposition can induce conductivity in insulating PCBM thin films, which is thermally–activated process following the 3D variable range hopping model. This conductivity is supposed to be attributed to hopping process between in-gap states due to newly formed PCBM-Au compounds as disordered hopping sites, which should significantly depend on spatial distribution of PCBM-Au compound because localization due to disorder is a common origin of the insulating behavior of low-dimensional electron systems. We performed in-situ I-t measurement in the course of Au deposition on PCBM film (conductivity as a function of Au deposition level) on three samples fabricated on SiO2/Si substrate with comb-like Au/Cr electrodes; amorphous PCBM film, crystalized PCBM, and control sample without PCBM. In this study, we controlled crystallization of PCBM by changing annealing temperature; PCBM crystallizes at annealing temperature of 260°C.
In Fig.1, the conductivities of PCBM/Au systems are found to depend dramatically on change of spatial distribution of PCBM by crystallization; change of disorder in samples.Details will be discussed at conference.
[1] T. Chen, et al., Nature 577, 341 (2020).
We found that small amount of Au deposition can induce conductivity in insulating PCBM thin films, which is thermally–activated process following the 3D variable range hopping model. This conductivity is supposed to be attributed to hopping process between in-gap states due to newly formed PCBM-Au compounds as disordered hopping sites, which should significantly depend on spatial distribution of PCBM-Au compound because localization due to disorder is a common origin of the insulating behavior of low-dimensional electron systems. We performed in-situ I-t measurement in the course of Au deposition on PCBM film (conductivity as a function of Au deposition level) on three samples fabricated on SiO2/Si substrate with comb-like Au/Cr electrodes; amorphous PCBM film, crystalized PCBM, and control sample without PCBM. In this study, we controlled crystallization of PCBM by changing annealing temperature; PCBM crystallizes at annealing temperature of 260°C.
In Fig.1, the conductivities of PCBM/Au systems are found to depend dramatically on change of spatial distribution of PCBM by crystallization; change of disorder in samples.Details will be discussed at conference.
[1] T. Chen, et al., Nature 577, 341 (2020).