Structural and optical properties of Zn 1-x Mg x O films grown by pulsed laser deposition

Abstract

Zinc oxide is a promising a wide band gap material for optoelectronic applications. Alloying ZnO with MgO gives the possibility of band gap tuning and fabrication of engineered heterostructures for optoelectronic applications. In this paper we report the growth of c-axis oriented crystalline Zn 1-x Mg x O thin films on amorphous silica and p-type silicon (100) substrates by pulsed laser deposition. The dependence of optical properties on Mg content in the Zn 1-x Mg x O films were investigated. All the films are highly transparent in the visible region. The scanning electron microscope (SEM) images shows the films are very smooth. Heterojunction diodes were fabricated by depositing n-type Zn 1-x Mg x O on p-type silicon. Rectification is observed with a ratio of forward to reverse current as high as 1000 in the range -5 to +5 V. The forward bias current-voltage characteristics indicate the current is dominated by single carrier injection in to the p-Si. The capacitance measurements show a strong frequency dispersion, which can be attributed to the traps at the interface.