Magneto-Optical Properties of Bound Excitons in ZnO

TL;DR

This study investigates the magneto-optical properties of bound excitons in ZnO, revealing insights into valence band symmetry and effects of nitrogen doping on exciton complexes through experimental and theoretical analysis.

Contribution

It provides new experimental and theoretical insights into the magneto-optical behavior of bound excitons in ZnO, especially regarding nitrogen doping effects and valence band symmetry.

Findings

Valence band has $b7$ symmetry.

Nitrogen doping creates acceptor centers.

Donor bound excitons are identified in nitrogen-doped ZnO.

Abstract

We present results of magneto-optical measurements and theoretical analysis of shallow bound exciton complexes in bulk ZnO. Polarization and angular dependencies of magneto-photoluminescence spectra at 5 T suggest that the upper valence band has $\Gamma_7$ symmetry. Nitrogen doping leads to the formation of an acceptor center that compensates shallow donors. This is confirmed by the observation of excitons bound to ionized donors in nitrogen doped ZnO. The strongest transition in the ZnO:N ($I_9$ transition) is associated with a donor bound exciton. This conclusion is based on its thermalization behavior in temperature-dependent magneto-transmission measurements and is supported by comparison of the thermalization properties of the $I_9$ and $I_4$ emission lines in temperature-dependent magneto-photoluminescence investigations.