Zinc oxide based films are transparent conductive oxide materials. As part of our research in solar cells, Al- and P-doped ZnO films were prepared at 250 °C in a hot-wall atomic layer deposition (ALD) system. Ozone, diethylzinc, trimethylaluminum or trimethylphosphite were used as the precursors. We obtained films with different Al or P concentrations by varying the precursor vapor pressures, and characterized their physical, chemical and electrical properties. The Al-doped films were n-type with the lowest resistivity occurring at an Al concentration of 1-2%. The as-deposited P-doped films were n-type, but upon rapid thermal annealing in oxygen, the films changed to p-type. The temperature of the n- to p-type transition decreased as the phosphorus concentration increased.

 

In this presentation, we will describe details of the Auger electron spectroscopic (AES) and X-ray photoelectron spectroscopic (XPS) measurements. AES depth profiling was used to determine the compositions of all of the films, which confirmed that a layered microstructure for the films prepared by introducing the Zn precursor and Al precursor alternatively, and a homogeneous distribution of the Al in the films prepared by co-injecting the Al and Zn precursors. XPS determined the compositional change of the oxygen species upon sputtering. The oxidation state of the P dopant was determined to be +5 for both the as-deposited and annealed films.