Cu-doped ZnO-based p-n hetero-junction light emitting diode

Abstract

Copper-doped p-ZnO thin films (Cu:ZnO) were grown on alpha-Al2O3(0001) and 6H: SiC(0001) single crystal substrates by plasma-assisted molecular beam epitaxy. A p-n hetero-junction with p-Cu:ZnO/n-6H:SiC was successfully fabricated and demonstrated as a greenish-blue light emitting diode ( LED). The rectifying I-V curve along with the matching photoluminescence and electroluminescence emissions characterizes the fabricated p-n hetero-junction LED. The Cu cell temperature (TCu) and the post-deposition annealing environment greatly influence the Cu oxidation state, and hence the electrical conversion from n-type to p-type and carrier concentration in the films. The higher TCu and post-annealing in O-plasma were observed to be the favorable conditions for Cu2+ and hence the p-type nature of the films.