Enhanced photocurrent of Ge-doped InGaO thin film transistors with quantum dots

Sang Moo Lee, Si Jin Park, Kwang Ho Lee, Jin Seong Park, Soohyung Park, Yeonjin Yi, Seong Jun Kang

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23 Citations (Scopus)


The photocurrent of germanium-doped indium-gallium oxide (GIGO) thin film transistors (TFTs) can be observed when the device is exposed to a ultra-violet light because GIGO is a wide band gap semiconducting material. Therefore, we decorated cadmium selenide (CdSe) quantum-dots (QDs) on the surface of GIGO to increase the photocurrent for low-energy light, i.e., visible light. A 10 nm GIGO film was deposited on the SiO2/Si substrate by a radio frequency sputter system. Also, we prepared CdSe QDs with sizes of ∼6.3 nm, which can absorb red visible light. QDs were spin-coated onto the GIGO film, and post-annealing was done to provide cross-linking between QDs. The prepared devices showed a 231% increase in photocurrent when exposed to 650 nm light due to the QDs on the GIGO surface. Measurements to construct an energy level diagram were made using ultraviolet photoelectron spectroscopy to determine the origin of the photocurrent, and we found that the small band gap of CdSe QDs enables the increase in photocurrent in the GIGO TFTs. This result is relevant for developing highly transparent photosensors based on oxide semiconductors and QDs.

Original languageEnglish
Article number031112
JournalApplied Physics Letters
Issue number3
Publication statusPublished - 2015 Jan 19

Bibliographical note

Publisher Copyright:
© 2015 AIP Publishing LLC.

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)


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