A postdeposition thermal treatment has been applied to sputtered Al-doped zinc oxide films and shown to strongly decrease the resistivity of the films. While high temperature annealing usually leads to deterioration of electrical transport properties, a silicon capping layer successfully prevented the degradation of carrier concentration during the annealing step. The effect of annealing time and temperature has been studied in detail. A mobility increase from values of around 40 cm2/Vs up to 67 cm2/Vs, resulting in a resistivity of 1.4×10−4 Ω cm has been obtained for annealing at temperatures of 650 °C. The high mobility increase is most likely obtained by reduced grain boundary scattering. Changes in carrier concentration in the films caused by the thermal treatment are the result of two competing processes. For short annealing procedures we observed an increase in carrier concentration that we attribute to hydrogen diffusing into the zinc oxide film from a silicon nitride barrier layer between the zinc...

/pdf/improved-electrical-transport-in-al-doped-zinc-oxide-by-4yvszh56gs.pdf

Improved electrical transport in Al-doped zinc oxide by thermal treatment

http://eportfolio.lib.ksu.edu.tw/~G980J013/repository/fetch/Optical,%20electrical%20and%20structural%20characteristics%20of%20AlZnO%20thin%20films.pdf

Optical, electrical and structural characteristics of Al:ZnO thin films with various thicknesses deposited by DC sputtering at room temperature and annealed in air or vacuum

Effect of nickel doping on the photocatalytic activity of ZnO thin films under UV and visible light

http://www.huepkes.de/files/berginski_toeo_2007.pdf

Recent development on surface-textured ZnO:Al films prepared by sputtering for thin-film solar cell application

Spray-deposited Al-doped ZnO transparent contacts for CdTe solar cells

The resistivity and the thermal stability of transparent conducting ZnO layers doped with aluminum have been correlated with the conditions of the sputtering process. Layers deposited at low rf power density (∼1.3 to 2.6 W/cm2) exhibit a low resistivity of 9×10−4 Ω cm, predominantly due to a high concentration of intrinsic donor type defects. These donors are compensated during annealing at high temperature in a vacuum; the low resistivity increases and the layers are not thermally stable. At rf power densities of ∼3.2 W/cm2 and more, the deposition conditions yield a high growth rate and the extrinsic aluminum dopant is incorporated on vacant cation sites. These substitutional donors are thermally stable therefore a low resistivity is retained after annealing at 550 °C.

/pdf/influence-of-deposition-conditions-on-the-thermal-stability-ut1v7u3u7b.pdf

Zs. Geller

Papers

Influence of deposition conditions on the thermal stability of ZnO:Al films grown by rf magnetron sputtering