P-Type ZnO Films Made by Atomic Layer Deposition and Ion Implantation

Area of Science:

• Materials Science
• Semiconductor Physics
• Solid State Chemistry

Background:

• Zinc oxide (ZnO) is a wide bandgap semiconductor with significant optoelectronic potential.
• Native defects in ZnO typically lead to n-type conductivity, making p-type doping a critical challenge.
• Stable p-type ZnO is essential for advanced electronic and photonic device applications.

Purpose of the Study:

• To investigate the electrical and optical properties of ex situ doped p-type ZnO films.
• To explore methods for achieving stable p-type conductivity in ZnO through ion implantation.
• To compare the effects of different annealing techniques on doping efficiency and material properties.

Main Methods:

• Ion implantation of group V elements (Phosphorus and Antimony) into ZnO.
• Post-implantation annealing using Rapid Thermal Annealing (RTA) and Flash Lamp Annealing (FLA).
• Electrical characterization to determine carrier concentration and type, and microstructural analysis.

Main Results:

• Phosphorus-doped ZnO films demonstrated stable p-type conductivity with hole concentrations ranging from 10^14 to 10^18 cm^-3.
• Antimony implantation consistently resulted in n-type ZnO layers, irrespective of the annealing method.
• Microstructural analysis revealed metallic clusters in Sb-doped ZnO after millisecond annealing and Sb-oxide formation after RTA.

Conclusions:

• Stable p-type ZnO can be achieved using phosphorus ion implantation followed by appropriate annealing.
• Antimony is not a suitable dopant for achieving p-type ZnO with the methods employed.
• The annealing process significantly influences the resulting material structure and electrical properties of doped ZnO.