Independently driven four-probe method for local electrical characteristics in organic thin-film transistors under controlled channel potential

Abstract

We describe an independently driven four-probe method to investigate local channel mobility in organic field-effect transistors (OFETs). In OFET devices, probe-organic contact resistance affects device characteristics even in four-probe measurement because a change in contact resistance at the source probe induces a change in channel potential, resulting in different local carrier density. To overcome this problem, we introduced a feedback circuit between the source probe and a channel voltage probe to keep the channel potential constant. We demonstrate four-probe I-V measurement on a pentacene thin film (50 nm thick) under controlled channel potential. The feedback successfully enables us to separate contact resistance and channel resistance even under different contact conditions. We also measured four-probe resistance as a function of gate bias and channel probe position. The present results were in good agreement with two-dimensional model calculation by arranging four probes in a defect-free area; the mobility of the pentacene single grain was evaluated to be 0.25 cm(2)/(V s).

Progress and development in multiple-probe scanning probe microscopes

“…Iwata 等人 [82] 和Bolopion等人 [83] 分别开发了具有实时触觉 反馈的纳米镊子系统, 他们采用不同的偏转检测方 法, Iwata等人利用自检测探针, 而Bolopion等人采用 的是激光反射法. [59] , ZnO [60] QP-STM Bi 2 Se 3 [61] , CoSi 2 [43,62] 二维 DP-STM Au表面 [63] , 3-octylthiophene薄膜 [64,65] , 石墨烯 [66,67] DP-AFM α-sexithiophene [44] , 并五苯薄膜 [68] QP-STM 石墨烯 [69,70] , Si(111)4×1-In [71] , Bi 2 Te 2 Se表面 [72,73] , Pentacene薄膜 [74,75] , Au表面 [76] , Te/Si(111)-(1×1)界面 [77] 评 述 图 6 DP-AFM并行成像与操作 [33] . (a) 并行成像与操作纳米颗粒的示意图.…”

Instrumentation for dual-probe scanning near-field optical microscopy

“…Consequently, a scanning tunneling microscope (STM), [16][17][18][19][20][21][22][23][24] an atomic force microscope (AFM), [25][26][27] and a scanning near-field optical microscope (SNOM) (Refs. 15, 28, and 29) with multiple probes have been developed to characterize the correlation between local structures and optoelectronic characteristics.…”

“…Several methods have been proposed to resolve this issue, including monitoring the probes with an optical microscope or a scanning electron microscope (SEM), comparing the surface morphologies obtained by the two probes, and measuring the shape of the probe tip with another probe. Decreasing the distance between the two probes to less than a few micrometers is difficult when monitoring the probes with an optical microscope 24,27 because the spatial resolution is restricted by the diffraction limit. Although the multiple-tip STM installed in SEM achieved 30 nm of minimum distance between two probes, 22 in many cases, precisely controlling the position of the probe tip in SEM is difficult due to the charging effect of the sample.…”