白宝石衬底上生长的MgxZn1-xO晶体薄膜的结构和光学性能

在白宝石 (sapphire)衬底上低温外延生长出了MgxZn1 -xO晶体薄膜 .x射线衍射 (XRD)及能量色散x射线 (EDX)分析表明 ,MgxZn1 -xO薄膜的晶体结构依赖于薄膜中Mg的组分x,随着Mg组分的增大 ,MgxZn1 -xO薄膜的结构从与ZnO晶体一致的六方结构转变为与MgO晶体一致的立方结构 .对MgxZn1 -xO薄膜的紫外透射光谱及紫外光致荧光谱 (UVPL)的分析表明 ,随着Mg组分的增大 ,光学吸收边产生明显的蓝移 ,表明MgxZn1 -xO晶体薄膜的带隙增大 ,且带隙连续可调 .吸收光谱和XRD测量显示 ,带隙高达 5 6 5eV的MgxZn1 -xO晶体薄膜与MgO之间的晶格失配仅为0 16 % .

Structural and optical studies of MgxZn1-xO films grown on sapphire

Low-temperature epitaxy of Mg x Zn 1-x O thin films is achieved on sapphire substrates by the reactive electron beam evaporation. X-ray diffraction (XRD) and energy dispersive x-ray (EDX) analyses of the films demonstrate that the structure of Mg x Zn 1-x O depends upon the concentration of Mg in the films. With the increase of Mg concentration, the structure of Mg x Zn 1-x O changes from the wurtzite crystal structure of ZnO to the cubic one with lattice constant similar to that of MgO. By the measurements of UV-visible transmission and ultraviolet photoluminescence spectra of the Mg x Zn 1-x O films, it is found that the absorption band edge of Mg x Zn 1-x O is blue shifted obviously with the increase of Mg concentration, indicating the absorption band edge of Mg x Zn 1-x O becomes wider. However, the lattice mismatch between cubic Mg x Zn 1-x O film and MgO is small (0 16%).