退火对ZnO薄膜晶体结构和ZnO/p-Si异质结光电性质的影响

采用脉冲激光沉积方法在p-Si(100)衬底卜牛长ZnO薄膜,分别在500℃、600℃和700℃下真空退火,采用X射线衍射仪研究了退火对ZnO薄膜品体结构的影响,并测量了ZnO的面电阻和ZnO/p-Si异质结的、I-V特性曲线.研究表明,随着退火温度的升高,ZnO的(002)衍射峰强度逐渐增大,半峰全宽不断减小,同时薄膜内应力减小,ZnO晶粒尺寸变大.表明高温退火有助于ZnO薄膜结晶质量的提高.在没有光照的条件下,异质结的漏电流随退火温度的增加而增大;用650 nm光照射样品时,600℃退火的样品表现出最明显的光电效应,而过高的退火温度会破坏ZnO/p-Si异质结的界面结构,使其光电流变小.所以,要得到性能良好的光电器件,应选取适当的退火温度.     

Effects of Substrate Temperature and Nitrogen Pressure on Growth of AIN Films by Pulsed Laser Deposition

Highly oriented aluminium nitride （AIN） films are grown on p-Si （100） substrates by pulsed laser deposition, and their characteristics of structure and composition are studied by x-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The results show that the deposited films exhibit good crystalline properties with a sharp x-ray diffraction peak at 2θ= 33.15 ° corresponding to AIN h （100） crystalline orientation. The influences of substrate temperature and ambient nitrogen （N2） pressure on the crystallinity of A1N films are remarkable. At room temperature, when the ambient N2 pressure arises from 5 × 10^-6 Pa to 5 Pa, the crystallinity of the film becomes better. When the substrate temperature is 600℃, the film has the best crystallinity at 0.05 Pa. Furthermore, the effects of substrate temperature and ambient N2 pressure on the combination of A1-N bonds and surface morphology of AIN films are also studied.     

含分枝铜纳米线多孔铝膜的偏振特性

利用二次阳极氧化法制备了具有分枝结构的多孔铝(PAA)模板,并以交流电化学沉积的方法在该模板中合成了分枝状的铜纳米线。用SEM观察样品的形貌结构,用分光光度计测量了样品的透射光谱和偏振光谱。实验结果表明,含分枝状铜纳米线结构的多孔铝膜在近红外光区具有较高的透射率,且得到了14～22 dB的消光比。这种微偏振器件制备方法简单、效率高、造价低,在光电集成领域有着广泛的应用前景。     

Study of white light emission from ZnS/PS composite system

ZnS films were deposited by pulsed laser deposition(PLD)on porous silicon(PS)substrates formed by electrochemical anodization of p-type(100)silicon wafer.The photoluminescence(PL)spectra of ZnS/PS composites were measured at room temperature.Under different excitation wavelengths,the relative integrated intensities of the red light emission from PS layers and the blue-green emission from ZnS films had different values.After samples were annealed in vacuum at different temperatures(200,300,and 400℃)for 30 min respectively,a new green emission located at around 550 nm appeared in the PL spectra of all ZnS/PS samples,and all of the ZnS/PS composites had a broad PL band(450-700 nm)in the visible region,exhibiting intensively white light emission.     

Structural, Optical and Electrical Properties of ZnS/Porous Silicon Heterostructures

ZnS films are deposited by pulsed laser deposition on porous silicon （PS） substrates formed by electrochemical anodization of p-type （100） silicon wafer. Scanning electron microscope images reveal that the surface of ZnS films is unsmoothed, and there are some cracks in the ZnS films due to the roughness of the PS surface. The x-ray diffraction patterns show that the ZnS films on PS surface are grown in preferring orientation along cubic phase β-ZnS （111） direction. White light emission is obtained by combining the blue-green emission from ZnS films with the orange-red emission from PS layers. Based on the I-V characteristic, the ZnS/PS heterojunction exhibits the rectifying junction behaviour, and an ideality factor n is calculated to be 77 from the I-V plot.     

ZnO/P-Si异质结的光电特性研究

利用脉冲激光沉积方法在P-Si(100)衬底上生长ZnO薄膜,制备ZnO/P-Si异质结,研究衬底温度对异质结光电特性的影响.结果表明,在400℃,500℃,550℃和600℃下生长ZnO制备的异质结都有一定的整流特性,反向暗电流随着衬底温度的升高略有增加,在550℃下制备的样品具有最明显的光电效应.ZnO/P-Si异质结对可见光和紫外光呈现出不同的响应性.在可见光照射下,光电流随反向偏压急剧增大,偏压增大到某一值时,光电流增速变小,而在紫外光下,光电流有逐渐增大的趋势.根据ZnO的透射谱认为,可见光和紫外光是异质结不同的耗尽区诱导电子-空穴对产生光电流的.     

退火对溶胶-凝胶法制备的ZnO薄膜结构和光致发光的影响

采用溶胶-凝胶法在n-Si(100)衬底上制备ZnO薄膜并从三个方面对其研究。X射线衍射结果表明,在含氧气氛中退火的ZnO薄膜为多晶六角纤锌矿结构,有明显的c轴择优结晶取向;退火时间的长短和温度的高低对结晶取向性和粒径均有较大影响,通过进一步的研究发现最佳处理温度在500℃左右。用扫描电子显微镜观察样品的表面和侧面形貌,晶体的生长比较均匀,粒径平均在70~160nm范围内,与XRD测量结果相一致。室温下ZnO胶体的光致发光谱表明,随着胶体老化时间的延长,胶体的紫外峰位发生了蓝移。室温下ZnO薄膜的光致发光谱表明,紫外部分的发光峰位在365,390nm,发光强度较强;在可见光区的发光强度相对较弱,但是还没有被氧完全抑制掉。     

退火对ZnS/PS复合体系光致发光特性的影响

用脉冲激光沉积(PLD)技术以多孔硅(PS)为衬底生长了ZnS薄膜,分别测量了ZnS、PS以及ZnS/PS复合体系在室温下的光致发光(PL)光谱。结果发现,ZnS/PS复合体系的PL光谱中PS的发光峰位相对于新制备的PS有所蓝移。把该ZnS/PS样品分成三块,在真空400℃分别退火10,20,30 min,研究不同退火时间对ZnS/PS复合体系光致发光特性的影响。发现退火后样品的PL光谱中都出现了一个新的绿色发光带,归结为ZnS的缺陷中心发光。随着退火时间的延长,PS的发光强度逐渐降低且峰位红移。把ZnS的蓝、绿光与PS的红光相叠加,整个ZnS/PS复合体系在可见光区450~700 nm形成一个较宽的光致发光谱带,呈现较强的白光发射。