Ultra-low-resistivity nitrogen-doped p-type Cu2O thin films fabricated by reactive HiPIMS

TL;DR

This study demonstrates the fabrication of nitrogen-doped Cu2O thin films with ultra-low resistivity using reactive HiPIMS, revealing how energy regimes influence structure, composition, and optoelectrical properties for potential optoelectronic applications.

Contribution

It introduces a method to control electrical and optical properties of Cu2O films via reactive HiPIMS, highlighting the role of energy regimes in nitrogen incorporation and resistivity reduction.

Findings

Resistivity as low as 5 x10^-2 ohm·cm achieved.

High-energy regime preserves Cu2O structure and enhances nitrogen substitution.

DFT calculations suggest N2 molecules act as shallow acceptors.

Abstract

We have successfully fabricated the nitrogen-doped cuprous oxide thin films on the amorphous standard soda-lime glass by reactive high-power impulse magnetron sputtering. The energy of film-forming particles was controlled by the value of pulse-averaged target power density, which has a significant impact on the elemental composition, structure and optoelectrical properties of the films. We have shown that the high-energy regime is more suitable for preserving Cu2O structure and leads to continuous substitution of oxygen by nitrogen compared with the low-energy regime. Moreover, in the high-energy regime, it is possible, to some extent, to independently control the electrical resistivity and optical properties. The electrical resistivity decreases down to 5 x10-2 ohm.cm at the optical band gap 2.0-2.3 eV. Special attention is paid to the formation of nitrogen molecules and their ability to form shallow acceptor states. Experimental results supported by our DFT calculations indicate that N2 replacing Cu in the Cu2O lattice is one possible (but not the only possible) acceptor. We have also found that the formation of nitrogen molecules is preferred in a high-energy regime.