PL Property of Al-N Codoped p-type ZnO Thin Films Fabricated by DC Magnetron Sputtering

Abstract

High-quality Al-N doped p-type ZnO thin films were deposited on Si and buffer layer/Si by DC magnetron sputtering in a mixture of <TEX>$N_2$</TEX> and <TEX>$O_2$</TEX> gas. The target was ceramic ZnO mixed with <TEX>$Al_2O_3$</TEX> (2 wt%). The p-type ZnO thin films showed a carrier concentration in the range of <TEX>$1.5{\times}10^{15}{\sim}2.93{\times}10^{17}\;cm^{-3}$</TEX>, resistivity in the range of 131.2<TEX>${\sim}$</TEX>2.864 <TEX>${\Omega}cm$</TEX>, mobility in the range of 3.99<TEX>${\sim}$</TEX>31.6 <TEX>$cm^2V^{-1}s^{-l}$</TEX>, respectively. It was easier to dope p-type ZnO films on Si substrates than on buffer layer/Si. The film grown on Si showed the highest quality of photoluminescence (PL) characteristics. The Al donor energy level depth <TEX>$(E_d)$</TEX> of Al-N codoped ZnO films was reduced to about 50 meV, and the N acceptor energy level depth <TEX>$(E_a)$</TEX> was reduced to 63 meV.