Growth and characterization of Mg<i> _x </i>Zn₁ _&#x2212; <i> _x </i>O films grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>We report on the structural and optical properties of non polar a-plane Mg<I> <SUB>x</SUB> </I>Zn<SUB>1</SUB> <SUB>−</SUB> <I> <SUB>x</SUB> </I>O (0⩽ <I>x</I> ⩽0.57) films on r-plane sapphire substrates grown by plasma-assisted molecular beam epitaxy. Reflection high energy electron diffraction (RHEED) revealed a formation of cubic MgO phase when an Mg concentration increases. Room temperature (RT) photoluminescence (PL) and transmission electron microscopy consistently revealed the formation of cubic MgO phase from the Mg<SUB>0.21</SUB>Zn<SUB>0.79</SUB>O film. The Mg<SUB>0.11</SUB>Zn<SUB>0.89</SUB>O film showed a band edge emission at ∼360nm, which is a shorter wavelength than the ZnO (∼373nm), from the RT PL measurements. Photoluminescence excitation (PLE) measurements at RT showed that band-gap energies of Mg<I> <SUB>x</SUB> </I>Zn<SUB>1</SUB> <SUB>−</SUB> <I> <SUB>x</SUB> </I>O films could be tuned up to ∼4.65eV (∼270nm) although cubic MgO phase were mixed for high Mg concentration. For the single phase wurtzite MgZnO film, band-gap energy of 3.48eV was obtained from the Mg<SUB>0.11</SUB>Zn<SUB>0.89</SUB>O film.</P>