摘要
近紫外光发射氧化锌薄膜是一种新兴的发光材料 ,它的发光波长比氮化镓的蓝光波长更短 ,在光存储应用中可以进一步提高光存储的密度 ,因而在光电子领域具有重要应用价值而备受关注。在此介绍我们用直流反应溅射方法在硅衬底上生长的氧化锌薄膜 ,观察了它们的阴极射线发光和光致发光光谱 ,研究了发光与薄膜晶体结构 ,以及发光与激发电子束流的关系等。
ZnO films were deposited on Si substrates by using DC sputtering and their cathodeluminescence(CL) and photoluminescence(PL) properties at room temperature were investigated. The CL spectra of the ZnO films include three peaks.They are purple(center wavelength about 390nm),blue(430～450nm),and green(522～525nm) emissions.These spectra are dependent on the crystal quality of ZnO films.The purple peak appears only in the sample whose crystal quality is good.We also observed that the intensities of purple,blue and green emissions vary with CL electron beam current density .With the increase of electron beam current density,the intensity of blue peak increases almost linearly and the intensity of purple peak increases super linearly.According to these phenomena,it is deduced that the green emission results from the electron transition between a donor level caused by oxygen vacancies and an acceptor level caused by zinc vacancies.The blue emission includes two transitions of electrons : from the donor to the valence band and from the conduction band to the acceptor.The ultraviolet band would be the excition transition from the band edge emission.At the same time,the wavelength of purple peak exhibits red shift with increasing the CL electron beam current density .We suggest that the increasing carrier density generated by increasing exciting power cause the luminescence center to tend to gap tail levels. Except green,blue and purple peaks,a new ultraviolet peak (334nm) appears in the PL spectra of the ZnO films.The photon energy (3 72eV) of the ultraviolet peak is much larger than the band gap of ZnO.The reason needs to be investigated in further experiments.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2001年第2期167-171,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金 ( 5 9872 0 3 7)
安徽省科委自然科学基金 ( 9864 15 5 0 )
国家科委专项基金 (国科基字 [1998] 0 10号 )资助
