Photocurrent Engineering of Silicon Nanowire Field-Effect Transistors by Ultrathin Poly(3-hexylthiophene)

Chihun In, Daewon Kim, Young Geun Roh, Sang Won Kim, Hyangsook Lee, Yeonsang Park, Sangsig Kim, Un Jeong Kim, Hyunyong Choi, Sung Woo Hwang

Research output: Contribution to journalArticle

Abstract

Photoresponse on the silicon nanowire (SiNW) and organic semiconductor interfaces embedding an insulating barrier is understood by a photogating effect associated with charge separations. Still elusive one is when the thickness of organic semiconductor is decreased down to a few molecular layers, where the photoresponse can be strongly altered by the spatial confinement of photoinduced carriers. In this work, the photoresponse modulation of SiNW field-effect transistors coated with an ultrathin organic semiconductor poly(3-hexylthiophene) (P3HT) is reported, where the P3HT layer thickness is changed by an order of magnitude. In the absence of laser illumination, the P3HT interface on SiNW slightly decreases the SiNW channel current, irrespective of the P3HT thickness. Upon the laser illumination, the thick case of P3HT layers (≈100 nm) supports the dissociation of photoinduced electrons and holes, hence the photogating effect largely decreases the SiNW channel current. When the P3HT layer thickness is decreased down to the P3HT hole diffusion length (≈8.5 nm), the photoinduced P3HT holes screen out the P3HT interface states, effectively increasing the SiNW channel current up to the intrinsic level. The method of engineering the organic semiconductor thickness suggests a complementary optoelectronic operation, verifying the controllable photoresponse within a compact nanodevice.

Original languageEnglish
Article number1801270
JournalAdvanced Materials Interfaces
Volume5
Issue number24
DOIs
Publication statusPublished - 2018 Dec 21

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering

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    In, C., Kim, D., Roh, Y. G., Kim, S. W., Lee, H., Park, Y., Kim, S., Kim, U. J., Choi, H., & Hwang, S. W. (2018). Photocurrent Engineering of Silicon Nanowire Field-Effect Transistors by Ultrathin Poly(3-hexylthiophene). Advanced Materials Interfaces, 5(24), [1801270]. https://doi.org/10.1002/admi.201801270