PLD工艺制备高质量ZnO／Si异质外延薄膜

Fabrication of high-quality ZnO/Si heteroepitaxial films by pulsed laser deposition

采用脉冲激光沉积工艺在不同条件下以Si(111)为衬底制备了ZnO薄膜。通过对不同氧压下(0～50Pa)沉积的样品的室温PL谱测试表明,氧气氛显著地提高了薄膜的发光质量,在50Pa氧气中沉积的ZnO薄膜具有最强的近带边UV发射。XRD测试说明在氧气氛中得到的薄膜结晶质量较差,没有单一的(002)取向。利用一低温(500℃)沉积的ZnO薄膜作缓冲层,得到了高质量的ZnO外延膜。与直接沉积的ZnO膜相比,生长在缓冲层上的ZnO膜展现出规则的斑点状衍射花样,而且拥有更强的UV发射和更窄的UV峰半高宽(98meV)。对不同温度下沉积的缓冲层进行了RHEED表征,结果表明,在600～650℃之间生长缓冲层,有望进一步改善ZnO外延膜的质量。

ZnO films have been synthesized on Si（111） substrates by pulsed laser deposition （PLD） under various conditions. For the specimens deposited at different oxygen pressures between 0 and 50Pa, room-temperature （RT） photoluminescence （PL） measurement indicates the optical properties are dramatically enhanced by introducing oxygen into the growth chamber. The specimen deposited at 50 Pa possesses the most intensive nearband-edge （NBE） emission. However, XRD results show the structural properties of ZnO thin films prepared in oxygen ambient is poor without a single （002） orientation. High-quality ZnO epitaxial film was fabricated by utilizing a low-temperature （500℃） deposited homo-buffer layer. Compared with the film without the buffer, the film with the buffer exhibits aligned spotty RHEED pattern, stronger ultraviolet （UV） emission, and smaller full width at half maximum （FWHM） of 98meV. RHEED patterns of buffer layers deposited at different temperatures suggest that the present properties of the ZnO epitaxial film may be improved further if the buffer is grown in a temperature range of 600-650℃.