Room Temperature Deposition of Highly Transparent n-ZnO on PET and ZnO Semiconductor FET

Abstract

In this paper we report on the fabrication of n-doped ZnO and semiconducting n-ZnO at room temperature by a new ablation deposition technology that makes use of electron/plasma ablation sources named Pulsed Plasma Deposition (PPD) developed by Organic Spintronics Srl.

The oxygen vacancies n-doped ZnO PPD grown thin film is deposited on PET and shows a resistivity of 3 × 10⁻⁴ohm cm. The n-ZnO TCO is compact, smooth and highly transparent in the UV-VIS (better than 90 T%) as well as in the near IR spectral range and it is remarkably temperature stable. Typical ZnO deposition rate of the PPD is 500 nm/min.

The RT deposited semiconductor ZnO shows a very large Hall electron mobility up to 1000 cm²/Vs approaching that of the single crystal. Preliminary results of Si/SiO₂ based bottom gate and contact FET test pattern structures with a 50 nm overlaying ZnO thin film shows an ON/OFF ratio of 50000 and a FET mobility of 1 cm²/Vs. Further implementation on appropriate FET design will be performed to explore the possibility to achieve a larger FET mobility. The PPD proves to be an enabling technology that makes it possible the advent of flexible OLED displays.