The Doped Properties Of Zinc Oxide Thin Films

Zinc oxide (ZnO) that is aⅡ-Ⅵgroup semiconductor with wide band-gap has aroused wide concern among the people, because it has some excellent optical and electrical properties that are aroused with exciton binding energy that reach 60meV at room temperature. ZnO is widely applied in many different fields, such as transparent conducting films, surface acoustic wave devices and short wabelength photonic devices and so on. But the various properties of intrinsic ZnO, such as conductivity, carrier concentration and photoluminescence and so on, cannot achieve level of devices development as it present weaker n-type conductivity. In general, this problem is solved by doped some specific elements with a certain concentration. As far as ZnO is concerned, to prepare n-type film with high quality is easy, but p-type with stable properties is difficult.In this paper, high quality n-type ZnO:Al film with doping Al element was prepared by pulsed laser deposition(PLD) technique, and p-type ZnO:N film with doping N element was prepared by hollow cathode deposition(HCD) technique. The specific study content is as follows:1. ZnO thin film with different doping Al concentration was deposited above quartz glass substrate by PLD (the temperature of substrate:200℃). The results of XRD and FESEM show that the (002) orientation of ZnO:Al thin films weakens with increasing Al concentration. The photoluminescence (PL) spectrum indicates that doping Al can form single ultraviolet stimulated emission of ZnO thin films, and restrain deep-level photoluminescence effectively.2. ZnO:Al (2.0wt.%Al) thin film deposited at 200℃has lowest resistivity and higher carrier concentration and mobility. Moreover, it display single ultraviolet stimulated emission that only less than intrinsic ZnO and has not visible light emission. It's light transmittance in visible light more than 80%.3. ZnO:Al thin film that was deposited at different temperature (100-200℃) has all light emission, and optical absorption edge arise blue shift when the deposition temperature is 200℃.4. ZnO:N thin film that was deposited by HCD at 200℃for 60min in nitrogen atmosphere above the substrate of pure ZnO films has good crystallization quality. XPS spectrum shows that doping concentration of N atom is higher in ZnO. The result of Hall effect show that resistivity of the ZnO:N film that was deposited with above parameters is only 0.1039Ω·cm, and carrier concentration up to 2.86×1020cm-3. Moreover, it's conductivity type is p-type. 5. ZnO:N film that was deposited by HCD with pure Zn in N2O atmosphere has good crystallization quality and doping N concentration, but the carrier concentration is only 6.5×1011cm-3.Its conductivity type is n-type. A comparison show that ZnO:N film that was deposited with N2 as doping N source has preferable electrical properties.