Formation of ZnO Thin Films and ZnO/GaN LEDs Using a Homemade Atmospheric-Pressure Plasma Jet Assisted with an Ultrasonic Atomizer
Jih-Shang Hwang1*, Chen-Ying Chou1, Fang-Yu Fu1, Shao-Chin Tseng1,2, Kuei-Hsien Chen3, Li-Chyong Chen4
1Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung, Taiwan
2National Synchrotron Radiatio, Hsin-Chu, Taiwan
3Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
4Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
* Presenter:Jih-Shang Hwang,
In this report, thin film deposition of ZnO as well as a ZnO/GaNLED is realized usnig an atmospheric pressure plasma jet (APPJ), which features significant reduction of the overall cost of the thin film deposition equipment. Our experimental results includes mainly 3 parts. First, we succeeded in growth of (0002) preferred orientated ZnO on quartz with a 600°C substrate temperature, proving the feasibility of high quality thin film deposition using the APPJ. The basic physical properties of the deposited ZnO films were also investigated. The absorption measurement shows that the band gap of the ZnO thin films is around 3.27eV. The UV peak in photoluminescence spectrum is located at 380nm (Eg = 3.26eV), and a visible PL band can be seen at 480nm. Second, we have succeeded in zinc oxide epitaxy on gallium nitride employing the APPJ. The rocking curve half-width reaches 1524 arcsec, which can still be further improved if the substrate temperature can be further increased. Third, we successfully prepared n-type zinc oxide / p-type gallium nitride light-emitting diodes, which not only emitted a near band edge UV light (370nm) from ZnO, but also emitted a 437nm blue light from p-GaN. We believe that the use of APPJ to achieve epitaxial zinc oxide is only one of the APPJ's applications being explored. In the future, APPJ should be able to be used in more different areas, as a new and novel processing technique.

Keywords: LED, ZnO, GaN, atmospheric pressure plasma jet