低温缓冲层对氧化锌薄膜质量的影响

利用金属有机化学气相沉积(MOCVD)法,在Si衬底上外延生长ZnO薄膜。为了改善氧化锌薄膜的质量,首先在Si衬底上生长低温ZnO缓冲层,然后再生长高质量的ZnO薄膜。通过XRD、SEM、光致发光(PL)光谱的实验研究,发现低温ZnO缓冲层可有效降低ZnO薄膜和Si衬底之间的晶格失配以及因热膨胀系数不同引起的晶格畸变。利用低温缓冲层生长的ZnO薄膜的(002)面衍射峰的强度要比直接在Si上生长的ZnO薄膜样品的高,并且衍射峰的半高宽也由0.21°减小到0.18°,同时有低温缓冲层的样品室温下的光致发光峰也有了明显的增高。这说明利用低温缓冲层生长的ZnO薄膜的结晶质量和光学性质都得到了明显改善。

Effects of the Low-temperature Buffer Layer on the Properties of ZnO Thin Films

ZnO films were grown on Si substrates by using plasma-assisted metal-organic chemical vapor deposition (MOCVD) method. Low-temperature ZnO buffer layers deposited on Si substrates were used as intermediate layers for the growth. The samples were investigated by X-ray diffraction, Scanning electron microscope and photoluminescence (PL) spectra. It is discovered that the low-temperature buffer layer can reduce the lattice distortion caused by lattice misfit and difference of the thermal expansion coefficients. With a low-temperature grown ZnO buffer layer, the X-ray diffraction (XRD) of the ZnO film results a strong (002) diffraction peak. The full-width at half-maximum (FWHM) of the (002) ZnO peak becomes narrower and the value of it declines from 0.21° to 0.18°. Meanwhile, the PL spectra peak value of the sample at room temperature increases obviously. The crystal quality and optical properties of the ZnO films which are deposited at 610℃ on low-temperature buffer layer are improved significantly.