溶胶-凝胶法制备MgxZn1-xO及其特性

采用溶胶-凝胶法制备了不同组分(x=0.1～0.3)的MgxZn1-xO前驱体,并对它进行不同温度的热处理(550℃～1000℃).X射线衍射(XRD)结果表明,Mg0.1Zn0.9O具有和ZnO一样的衍射谱,为六方纤锌矿结构,而且随着热处理温度的升高,ZnO衍射峰的强度逐渐增强,半高宽不断减小;Mg元素掺杂浓度增大后,出现了MgO的峰位.扫描电子显微镜(SEM)显示Mg0.1Zn0.9O晶粒粒径分布较均匀;热处理温度升高,晶粒的尺寸不断变大.用室温荧光光谱(PL)分析了经过550～1000℃热处理获得的Mg0.1Zn0.9O粉末,结果发现除了550℃下处理的样品,其它都有紫外发射峰(350nm左右),而且随着热处理温度的升高紫外峰有明显的蓝移现象.     

N掺杂MgxZn1-xO薄膜结构和光学性质研究

采用溶胶-凝胶法在玻璃衬底上制备了N掺杂MgxZn1-xO薄膜.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射光谱、光致发光(PL)谱对N掺杂MgxZn1-xO薄膜样品的晶体结构、表面形貌和光学性能进行了研究.XRD结果表明所有样品均形成了MgZnO合金薄膜,没有观察到其它氧化物的衍射峰.样品的结晶质量越差,样品的表面形貌越不规则,但样品在可见光的透射率越强,甚至达到了95;.样品的禁带宽度随Mg含量的增加而增加,随N含量的增加而减小.所有样品的光致发光谱均观察到强的400 nm发光和弱的可见发光.400 nm的发光强度随Mg含量的增加而减弱,随N含量的增加而增强,认为薄膜在400 nm的发光来源ZnO的激子复合.     

纳米ZnS∶Cu薄膜及谐振腔的制备与特性研究

采用水浴法制备不同掺杂浓度ZnS:Cu纳米薄膜及相应谐振腔.X射线衍射表明,该纳米薄膜具有立方相的闪锌矿结构.光致荧光测量显示,ZnS:Cu薄膜在2.37 eV处有很强的荧光峰.荧光强度与Cu/Zn物质的量比有关,当Cu/Zn物质的量比为0.1%时,ZnS:Cu纳米薄膜荧光强度最强.在由Al膜与ITO薄膜构成的腔长为3.6 μm的ZnS:Cu垂直谐振腔中共观察到10多个荧光干涉峰.经分析确定,该垂直谐振腔的品质因数为30.3.     

(111)择优取向ZnS薄膜的制备及特性研究

采用激光分子束外延技术在Al2O3衬底上成功外延生长了ZnS薄膜.用X射线衍射、扫描电子显微镜和光致发光谱表征了衬底温度对薄膜结构、形貌和光学特性的影响.结果表明所生长的ZnS薄膜为闪锌矿,具有(111)择优长向,随衬底温度的升高,X射线衍射峰的半高宽先减小后增大,在衬底温度为300℃时,半高宽最窄.薄膜结构致密,表面不平整度随衬底温度的升高而增大.薄膜的带隙随衬底温度的升高出现蓝移,可见光区域透射率最高达到98;,在360 nm激发波长下,观测到402 nm和468 nm两个发光带,衬底温度为300℃时,发光最强.     

MOCVD法在(220)CaF2衬底上生长ZnO薄膜及其性能研究

采用金属有机化学汽相沉积(MOCVD)法在(220)CaF2衬底上外延生长ZnO薄膜.利用X射线衍射(XRD)、紫外-可见光谱和光致发光谱(PL)对ZnO薄膜的结构和光学性能进行了分析.XRD结果表明,所制备的ZnO薄膜结晶性能良好,具有高度的(002)的择优取向,002衍射峰的半高宽(FMHM)为0.115°.所制备的ZnO薄膜透明,透过率超过85;.在常温的(He-Cd激光器)PL谱中,只有378.5 nm的带边发射.用同步辐射光源测试的真空紫外光谱中,在低温20K时,出现218 nm、368 nm、418 nm、554 nm发光峰,其中368 nm峰强度随着温度的升高强度逐渐下降,到常温时几乎消失.     

声化学法制备ZnS: Mn纳米晶及其光学性能

以无水氯化锌,四水氯化锰以及硫代乙酰胺为原料,采用声化学法成功制备了锰掺杂的ZnS(ZnS: Mn)纳米晶.采用透射电子显微镜镜(TEM)、X射线能谱仪(EDS)、X射线粉末衍射(XRD)和光致发光谱(PL)对所制得的纳米进行了表征.结果表明:所制备ZnS: Mn为立方闪锌矿结构,纳米粒子的形貌接近于球形.平均晶粒尺寸为10 nm左右.PL光谱分析表明:所制备试样有两个主要的发射峰,分别位于在480 nm和570 nm左右,后者与体材料ZnS: Mn相比发生了明显蓝移,但仍表现为橙黄色发光.Mn2+掺杂浓度对ZnS: Mn的光致发光性能有显著影响,原料中Zn: Mn: S(物质的量比)为3: 1: 4,Mn2+掺杂浓度为2.64 at;时,光致发光光谱发射峰强度达到最大值.     

硅太阳电池用MgF2/ZnS双层减反射薄膜的制备及表征

采用真空热蒸发技术,制备出了性能优良的MgF2/ZnS双层减反射薄膜.采用扫描电子显微镜、X射线衍射仪对薄膜的形貌以及结晶形态进行分析,采用椭圆偏振仪测试薄膜的折射系数及厚度,利用反射谱对双层减反射薄膜的减反射性能进行了表征.研究表明:衬底温度为200 ℃时薄膜附着力、结晶态良好;蒸发速率影响薄膜的表面形态;MgF2/ZnS厚度为110 nm/35 nm时具有最佳减反射效果.     

MgZnO/ZnO异质结构的发光性质研究

本文利用等离子体辅助分子束外延(P-MBE)技术在蓝宝石 (Al2O3) 衬底上生长了Mg0.12Zn0.88O(100nm)/ZnO (20nm) /Mg0.12Zn0.88O (40nm) 异质结构,测得样品的X射线衍射谱表明,在34.56°的位置出现很强的(002)方向衍射峰,其半高宽度为0.20°,比Mg0.12Zn0.88O合金薄膜的半高宽度0.15°明显展宽.通过光致发光谱研究了MgZnO/ZnO/MgZnO异质结构的光学性质,室温下测得在370nm(3.35eV)位置有很强的紫外发光,而在348nm (3.56eV)的位置处有一个较弱的发光,这两个峰分别被归结于来自ZnO层和MgZnO盖层的发光.室温下的吸收光谱中,在上述两个峰的位置附近分别存在很明显的吸收,指示了带边吸收来自于MgZnO和ZnO两种材料.通过变温发光谱研究了异质结构中载流子弛豫、复合的规律.随着温度增加,来自于ZnO层和MgZnO层的发光强度比增加,这归结为MgZnO/ZnO异质结构存在界面势垒所致.     

空气退火对ZnS薄膜结构和光学特性的影响

采用X射线衍射、扫描电子显微镜和光致发光等技术研究了空气退火对ZnS薄膜的结构和光学特性的影响.薄膜在500℃以下退火后结晶质量得到改善,仍呈ZnS立方相结构.退火温度达到550℃时,薄膜中出现ZnO六方相结构.薄膜退火后,大气中的氧掺入薄膜中,出现ZnS-ZnO复合层.随退火温度升高,薄膜晶粒尺寸增大,透过率增加,带隙逐渐接近ZnO带隙.薄膜光致发光结果表明,复合层内ZnS和ZnO绿色发光的叠加替代了来自ZnS缺陷能级间的绿色发光.     

温度对Ga掺杂ZnS纳米结构的形貌及光致发光性能的影响

分别以Zn粉和S粉为原材料,Ga为掺杂剂,Au纳米颗粒为催化剂,采用低温化学气相沉积法(CVD),在Si(l00)衬底上制备了Ga掺杂的ZnS纳米结构.利用X射线衍射仪(XRD)、能量弥散X-ray谱(EDS)、场发射扫描电子显微镜(SEM)和光致发光光谱(PL)等测试手段对样品的结构、成分、形貌和发光性能进行了分析.结果表明:随着温度的升高(450～ 550℃),Ga掺杂ZnS纳米结构的形貌发生了从蠕虫状纳米线到光滑纳米线再到纳米棒的演变,所制备的Ga掺杂的ZnS纳米结构均为六方纤锌矿结构,分别在波长为336 nm和675 nm处存在一个较强的近带边紫外发射峰和一个Ga掺杂引起的微弱红光峰,而其它发光峰均是缺陷引起的.此外,本文还对Ga掺杂ZnS纳米结构的形成过程进行了探讨,并提出了可能的形成机理.     

Photoluminescence characteristics of Mg- and Si-doped GaN thin films grown by MOCVD technique

We have studied the optical, structural and surface morphology of doped and undoped GaN thin films. The p- and n-type thin films have been successfully prepared by low-pressure MOCVD technique by doping with Mg and Si, respectively. The different carrier concentrations were obtained in the GaN thin films by varying dopant concentrations. Photoluminescence (PL) studies were carried to find the defect levels in the doped and undoped GaN thin films at low temperature. In the undoped GaN thin films, a low intensity and broad yellow band peak was observed. The donor–acceptor pair (DAP) emission and its phonon replicas were observed in both the Si or Mg lightly doped GaN thin films. The dominance of the blue and the yellow emissions increased in the PL spectra, as the carrier concentration was increased. The XRD and SEM analyses were employed to study the structural and surface morphology of the films, respectively. Both the doped and the undoped films exhibited hexagonal structure and polycrystalline nature. Mg-doped GaN thin films showed columnar structure whereas Si-doped films exhibited spherical shape grains.     

在脉冲纳米锌晶种上水热合成ZnS薄膜及其光学性能研究

用水热法在脉冲电沉积纳米Zn晶种的衬底上,制备了ZnS薄膜.利用XRD、SEM、EDS对ZnS薄膜结构进行了表征,通过UV、PL研究了ZnS薄膜的光学性质.结果表明,Zn晶种的存在、形貌控制剂(5-磺基水杨酸)的添加对ZnS薄膜显微形貌有重大影响.所制备出的ZnS薄膜为沿(106)晶面生长的六方纤锌矿结构,薄膜组成均匀而致密,光学禁带宽度变宽,发蓝紫光.     

High intense UV-luminescence of nanocrystalline ZnO thin films prepared by thermal oxidation of ZnS thin films

High quality zinc oxide (ZnO) films were obtained by thermal oxidation of high quality ZnS films. The ZnS films were deposited on a Si substrate by a low-pressure metalorganic chemical vapor deposition technique. X-ray diffraction spectra indicate that high quality ZnO films possessing a polycrystalline hexagonal wurtzite structure with preferred orientation of (0 0 2) were obtained. A fourth order LO Raman scattering was observed in the films. In photoluminescence (PL) measurements, a strong PL with a full-width at half-maximum of 10 nm around 380 nm was obtained for the samples annealed at 900°C at room temperature. The maximum PL intensity ratio of the UV emission to the deep-level emission is 28 at room temperature, providing evidence of the high quality of the nanocrystalline ZnO films.     

Structural and optical properties of Mg‐doped ZnO thin films prepared by a modified Pechini method

ZnO thin films with different Mg doping contents (0%, 3%, 5%, 8%, 10%, respectively) were prepared on quartz glass substrates by a modified Pechini method. XRD patterns reveal that all the thin films possess a polycrystalline hexagonal wurtzite structure. The peak position of (002) plane for Mg‐doped ZnO thin films shifts toward higher angle due to the Mg doping. The crystallite size calculated by Debey‐Scherrer formula is in the range of 32.95–48.92 nm. The SEM images show that Mg‐doped ZnO thin films are composed of dense nanoparticles, and the thickness of Mg‐doped ZnO thin films with Mg doped at 8% is around 140 nm. The transmittance spectra indicate that Mg doping can increase the optical bandgap of ZnO thin films. The band gap is tailored from 3.36 eV to 3.66 eV by changing Mg doping concentration between 3% and 10%. The photoluminescence spectra show that the ultraviolet emission peak of Mg‐doped ZnO thin films shifts toward lower wavelength as Mg doping content increases from 3% to 8%. The green emission peak of Mg‐doped ZnO thin films with Mg doping contents were 3%, 8%, and 10% is attributed to the oxygen vacancies or donor‐acceptor pair. These results prove that Mg‐doped ZnO thin films based on a modified Pechini method have the potential applications in the optoelectronic devices.     

Structural,optical and photoluminescence properties of ZnS: Cu nanoparticle thin films as a function of dopant concentration and quantum confinement effect

Thin films of ZnS: Cu nanoparticles were deposited in chemical bath by a pH controlled solution synthesis technique. The copper concentration was varied from 0 to 0.1M%. XRD and SEM indicated variations in diffracted intensity and morphology with Cu concentration. The PL spectrum of the undoped ZnS nanoparticles showed emission peaks at 393 and 432nm that could be attributed to the intrinsic defect states of ZnS nanoparticles. For ZnS: Cu samples three peaks in the range of 390nm, 480nm and 525nm were observed. With increase in Cu concentration from 0.001 to 0.1M%, the peak position of 480nm and 525nm did not change, whereas 390nm peak red shifted to longer wavelength region to 422nm. In addition, it was found that the overall photoluminescence intensity reached maximum at 0.01M% and quenched with further increase in Cu concentration. Enhancement of blue and green light emission by seven and twenty fivefold respectively compared to undoped ZnS was observed in ZnS: Cu with optimal dopant concentration. Time resolved decay of photoluminescence showed faster decay for 390 – 420nm purple/ blue emission compared to green (525nm) Cu related emission which is in the microsecond time scale. Optical absorption measurements indicate enhancement of band gap (3.89eV) for undoped ZnS suggesting the quantum confinement effect in the developed nanoparticles of size below the Bohr diameter. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

反相微乳液法制备CdS/ZnS纳米晶及其表征

用反相微乳液法制备了CdS纳米粒子,以ZnS对其表面进行包裹,得到了核壳结构的CdS/ZnS纳米晶.采用X射线衍射(XRD)、透射电镜(TEM)表征其结构、粒度和形貌,紫外-可见吸收光谱(UV-VIS)、光致发光光谱(PL)表征其光学特性.制得的CdS纳米微粒近似呈球形,直径约3.6nm;包裹以后颗粒仍为球形,粒径约10nm,以XRD、UV-VIS和PL证实了CdS/ZnS核壳结构的实现.文章还研究了不同Zn/Cd的摩尔比对CdS/ZnS纳米微粒光学性能的影响,UV-VIS谱表明随着壳层厚度的增加CdS/ZnS纳米晶的吸收带边有轻微的红移;PL谱表明壳层ZnS的包覆可减少CdS纳米微粒的表面缺陷,带边直接复合发光几率增大,且具有合适的壳层厚度时,CdS核层的发光效率有较大提高.     

氨水浓度对化学浴沉积的Zn(O,S)薄膜形貌、结构和性能的影响

采用化学浴法,以ZnSO4·7H2O和SC( NH2)2作为反应前驱物,C6H5O7 Na3·2H2O作为络合剂,NH3·H2O 作为辅助络合剂和缓冲剂制备Zn(O,S)薄膜.采用SEM、EDS、XPS、XRD和透射光谱分析方法,研究氨水浓度对化学浴法制备的Zn(O,S)薄膜形貌、成分、结构和光学性能的影响以及Zn(O,S)薄膜的形成机理.结果表明:Zn(O,S)薄膜是由ZnO和ZnS纳米颗粒混合组成的,ZnO具有纤锌矿结构,ZnS是以非晶相存在.随着反应溶液中氨水浓度的降低,薄膜中所包含的ZnO逐渐减少,ZnS逐渐增加,S/Zn原子比逐渐增加,透射率和光学带隙也逐渐增大.     

溶胶-凝胶法制备高Mg含量Zn1-x MgxO薄膜

采用溶胶-凝胶法在石英玻璃基板上制备了ZB1-xMgxO薄膜,研究退火温度对高Mg含量Zn0.5Mg0.5O薄膜的相组成、相偏析及紫外-可见透过光谱中吸收边移动的影响,当退火温度≤500℃时,Zn0.5Mg0.5O薄膜未发生相偏析现象,且400℃退火处理制备的Zn0.5Mg0.5O薄膜的紫外-可见透过光谱中吸收边蓝移最大.因此,对于高Mg含量Zn0.5Mg0.5O薄膜,退火温度是影响Mg2+在ZnO中固溶度的关键因素,且400℃是其理想的退火温度.在此条件下研究了不同Mg含量对Zn1-xMgO(x=0～0.8)薄膜带隙调节的影响,随着Mg含量的增加,其紫外-可见透过光谱中紫外光区吸收边呈现规律性蓝移,光学带隙值Eg从纯ZnO的3.3 eV调节至4.2 eV.     

非晶锗的低温晶化和光学特性研究

本文采用直流磁控溅射在(100)硅衬底上沉积了单层锗薄膜,分别用拉曼光谱和X射线衍射研究了薄膜的结晶性,通过对结晶性的研究发现,在衬底温度为200℃时溅射功率为150W时结晶性开始变好,功率增至250W的过程,锗薄膜的择优取向发生(220)向(331)的变化.这样在无金属掺杂的情况下得到了结晶性较好的样品.光致发光结果表明,非晶锗在可见光区有较强的发光现象,发光峰位中心分别在648.1nm和713.0nm.发光峰位不随晶粒尺寸变化而变化,但峰强对晶粒大小的依赖性很强,平均晶粒较大的锗薄膜在可见光区发光现象不显著.     

MgO相分离对MgxZn1-xO纳米粉体结构和光学性能的影响

采用溶胶-凝胶法制备了MgxZn1-xO(x=0,0.1,0.2,0.3,0.4,0.5)纳米粉体。X射线衍射谱表明:在较高的温度(850℃以上)下退火,MgxZn1-xO纳米粉体从单一的纤锌矿结构相中分离出MgO相的掺杂浓度x约为0.13,且随着x的增加,MgO相含量呈指数型增长。室温光致发光谱显示:MgO相分离对紫外与绿光发射的相对强度有直接的影响,随着MgO相分离的出现,紫外发光峰蓝移,并随着MgO相的增加,紫外发光峰的强度受抑,绿光发光峰变强。样品的室温透过率显示:MgxZn1-xO的禁带宽度在x=0.1时达到最大值并受MgO相分离的影响而减小。