超声处理对ZnO薄膜光致发光特性的影响

对于结晶状态好的ZnO薄膜，测量了其光致发光(PL)光谱，发射光谱中只发现了峰值波长约389 nm的近紫外光.样品进行超声处理后，发射谱中不仅观察到近紫外峰，又观察到波长约508 nm的绿光峰.绿光峰的强度比近紫外光的强度强得多，且近紫外峰红移.进一步的热处理使绿光峰大大增强.超声处理改变了ZnO薄膜的质量和结晶状态，使晶格中产生氧空位.处理过程中的热效应使得薄膜晶格振动加剧.当晶格振动加剧到一定程度，晶格中的氧脱离格点形成氧空位.510 nm左右的绿色发光峰是ZnO晶体中的氧空位产生的.薄膜的温度越高， 关键词： ZnO薄膜 超声 光致发光

Effect of ultrasonic treatment on ZnO film photoluminescence

The photoluminescence spectrum of ZnO film with high crystal quality has been measured. The peak of near-ultraviolet emission located at 389 nm has been observed. For the ZnO film treated by ultrasonic, not only the ultraviolet peak of ZnO, but also the strong green peak at 508 nm have been observed. It is also found that the intensity of the green peak (508 nm) is stronger than that of the ultraviolet peak. The ultraviolet peak also appears to have red-shift. The intensity of the green peak (508 nm) increases sharply with further heating. The crystal quality of ZnO films is changed by the ultrasonic treatment and oxygen vacancies are produced. The lattice vibration of film is aggravated in the treatment process. When the lattice vibration arrives at certain degree, the lattice oxygen leaves the lattice site to form oxygen vacancy, and the green peak (about 510 nm) is attributed to oxygen vacancies in the crystal. The density of oxygen vacancies depends on the ZnO film temperature. The higher the film temperaure, the greater the density of oxygen vacancy and the stronger the intensity of the green peak.