Optically detected magnetic resonance and optically detected ENDOR of shallow indium donors in ZnO

Resolved hyperfine structure was observed in time-resolved optically detected electron-paramagnetic-resonance (ODMR) spectra obtained via a donor-acceptor emission band of ZnO. Optically detected electron-nuclear double-resonance (ENDOR) experiments showed that the structure results from hyperfine interaction with ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$. The values measured for the $g$ and hyperfine tensors ($g_{\parallel }=1.957\mathrm{}$, $g_{\perp }=1.956\mathrm{}$, $\frac{A_{\parallel }}{h}=100.3\mathrm{}$ MHz, $\frac{A_{\perp }}{h}=100.1\mathrm{}$ MHz) lead to attribution of the ODMR spectrum to shallow indium donors.