Accurate Extraction of Charge Carrier Mobility in 4‐Probe Field‐Effect Transistors. (30th April 2018)

• Record Type: Journal Article
• Authors: Choi, Hyun Ho; Rodionov, Yaroslav I.; Paterson, Alexandra F.; Panidi, Julianna; Saranin, Danila; Kharlamov, Nikolai; Didenko, Sergei I.; Anthopoulos, Thomas D.; Cho, Kilwon; Podzorov, Vitaly
• Is Part Of: Advanced functional materials. Volume 28:Number 26(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-04-30
• Subjects: conjugated polymers -- field‐effect transistors -- mobility -- molecular crystals -- organic semiconductors; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201707105
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Charge carrier mobility is an important characteristic of organic field‐effect transistors (OFETs) and other semiconductor devices. However, accurate mobility determination in FETs is frequently compromised by issues related to Schottky‐barrier contact resistance, that can be efficiently addressed by measurements in 4‐probe/Hall‐bar contact geometry. Here, it is shown that this technique, widely used in materials science, can still lead to significant mobility overestimation due to longitudinal channel shunting caused by voltage probes in 4‐probe structures. This effect is investigated numerically and experimentally in specially designed multiterminal OFETs based on optimized novel organic‐semiconductor blends and bulk single crystals. Numerical simulations reveal that 4‐probe FETs with long but narrow channels and wide voltage probes are especially prone to channel shunting, that can lead to mobilities overestimated by as much as 350%. In addition, the first Hall effect measurements in blended OFETs are reported and how Hall mobility can be affected by channel shunting is shown. As a solution to this problem, a numerical correction factor is introduced that can be used to obtain much more accurate experimental mobilities. This methodology is relevant to characterization of a variety of materials, including organic semiconductors, inorganic oxides, monolayer materials, as well as carbon nanotube and semiconductor nanocrystal arrays. Abstract : It is shown that 4‐probe contact geometry, frequently used for extraction of contact‐corrected charge mobility in organic or inorganic semiconductors, oxides, monolayers, and other emergent electronic materials, can lead to a significant mobility overestimation due to longitudinal channel shunting by wide voltage probes. A numerical correction factor that can be used for obtaining much more accurate experimental mobilities is introduced.