High Mobility and Ultrafast Photoresponse in A Single ZnO Nanoparticle Phototransistor

WenHao Chang^1*, LinhNam Nguyen², ChiiDong Chen³, YannWen Lan⁴

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²The University of Danang, University of Technology and Education, Danang, Viet Nam
³Institute of Physics, Academia Sinica, Taipei, Taiwan
⁴Department of Physics, National Taiwan Normal University, Taipei, Taiwan

* Presenter:WenHao Chang, email:jp6cl6@gmail.com

Conventional film-structured polycrystalline semiconductor devices suffer from grain boundary scattering, which is responsible for low mobility and can even mask intrinsic transport properties. In this work, we show that devices containing only a ZnO single particle can exhibit mobility values one order higher than that of single-crystal nanowires. The ZnO nanoparticle was embedded inside a nanopore structure, surrounded by a gate electrode and connected to top and bottom electrodes. Due to the absence of inter-grain scattering and long traveling distance, we obtained relatively high mobility values of around 600 cm²/Vs at room temperature (300 K) and about 1100 cm²/Vs at low temperature (≈180 K). The devices also presented external quantum efficiency of 5.6x10⁷, responsivity of 1.39x10⁶ A/W, detectivity of 8.69x10¹² Jones, and a record-high photoresponse rise time of 90 μs. This single nanoparticle-based device could be an excellent candidate of phototransistors with high performances.

Keywords: ZnO, nanoparticle, field effect transistor, FET, mobility, detectivity, responsivity, photoresponse