气相外延生长的ZnSe单晶薄膜及电致发光

用窄空间外延方法,在GaAs(100)衬底上外延生长了ZnSe(100)单晶薄膜.实验条件是,T衬=550℃,T源=650℃,H2-HCl气流速率为0.4-0.45l/min,生长速率为0.25-0.3μ/h.外延片在700℃的Zn和MnCl2蒸气中处理40-60分钟,以降低ZnSe的电阻率及掺入杂质Mn.利用这一外延层制作了MS结发光二极管,在反向偏压下获得黄色电致发光.     

OMVPE硒化锌薄膜的生长与激光特性

本文叙述了在GaAs衬底上用有机金属气相外延(OMVPE)法生长单晶ZnSe薄膜的方法。研究了生长温度,硒锌比对外延膜光电性能的影响。发现生长温度在285℃可以得到表面光亮、结晶性好、低阻、高迁移率、深中心浓度低的外延层。以光泵浦作激发研究了OMVPE ZnSe薄膜的受激发射性质并测量其光学增益。利用ZnSe/GaAs的自然解理面形成的光反馈腔制成了激光器。该激光器的工作温度可以延续到150K。     

衬底温度对热壁外延ZnSe薄膜质量的影响

用热壁外延法在不同衬底温度条件下生长一系列ZnSe薄膜,并通过X射线衍射、喇曼散射以及光致发光技术对ZnSe薄膜质量作了研究。实验结果表明,随着衬底温度下降,ZnSe薄膜质量逐渐变差;当衬底温度低于300℃时,(100)ZnSe薄膜中有(111)孪晶出现;但同时发现衬底温度大于375℃时,衬底Ga原子对ZnSe外延层扩散严重。     

气相外延ZnSe单晶薄膜的蓝色电致发光

本文在300℃—700℃温度范围内,在GaAs衬底上气相外延生长了ZnSe单晶薄膜。讨论了衬底温度对外延层电学性质及光学特性的影响。ZnSe外延层经Zn气氛热处理后,发光特性大为改善。用处理后的ZnSe外延膜做成MIS发光二极管,首次得到了室温下气相外延ZnSe单晶薄膜的蓝色电致发光。     

Zn1—xMgxSySe1—y四元半导体合金的拉曼散射光谱研究

用分子束外延方法在GaAs(100)衬底上生长了Zn1-xMgxSySe1-y四元半导体合金薄膜。用X－射线衍射方法确定了外延层的结构和晶格常数。测量了这些样品在平行和垂直两种不同几何配置下的拉曼散射光谱并对其特性做了研究。从实验上观察到了四类不同的晶格振动模：类ZnSe的TO和LO模拟及类ZnS和类MgS的LO模，实验发现：在ZnSe和ZnSSe中加入Mg使得类ZnSe的TO和LO模的振动频率下降；同时，也使类ZnS模的频率随S的增加率减小。     

分子束外延ZnSe/GaAs材料的拉曼散射研究

用分子束外延(MBE)技术，在GaAa(100)衬底上生长了厚度从0．045μm到1．4μm的ZnSe薄膜。通过室温拉曼光谱的测量对ZnSe薄膜纵光学声子(Longitudinal-opticalphonon)的谱形进行了分析。用拉曼散射的空间相关模型定量分析了一级拉曼散射的型间相关长度与晶体质量之间的关系，结果表明ZnSe外延层的晶体质量随着外延层厚度的减薄是渐渐退化的，这是由于界面失配位错引入外延层所致，理论分析与实验结果相吻合。     

硒化锌的气相外延生长

采用改进的气相外延法在(100)GaAs衬底上外延生长了ZnSe单晶膜。最大生长速率为每小时10μm左右。淀积过程的激活能为10kcal/mol。在77K的温度下测量了外延膜的光致发光,4460Å附近可以观察到很强的蓝色发射。外延膜的电阻率～1.1Ω·cm。     

Si衬底上ZnSe外延膜的低压MOCVD生长

以硒化氢（H2Se）和二甲基锌为源材料，生长温度是300℃时，用低压金属有机化学气相沉积（LP－MOCVD）系统在Si(111)衬底上外延生长了ZnSe薄膜。通过X射线衍射（XRD）、扫描电子显微镜的能量色散（EDS）以及光致发光（PL）实验验证ZnSe外延膜的质量，在X射线衍射谱中只有一个强的ZnSe(111)面衍射峰，这说明外延膜是（111）取向的单晶薄膜，在能量色散谱中除了Si,Zn和Se原子外，没有观测到其他原子，说明ZnSe外延膜中杂质含量较少。ZnSe外延膜中Zn/Se原子比接近1，有较好的化学配比。在ZnSe外延膜的77K光致发光谱中没有观测到与深中心发射相关的发光峰，表明ZnSe外延膜的晶格缺陷密度较小。77K时的近带边发射峰447nm在室温时移至465nm附近。     

AlN缓冲层对ZnO薄膜质量的影响

采用脉冲激光沉积法以AlN为缓冲层在Si(100)衬底上制备了ZnO薄膜,并测量了样品的XRD谱、SEM图和PL谱.结果表明,AlN缓冲层可以提高Si衬底上外延生长ZnO薄膜的晶体质量.改变缓冲层的生长温度(50～500 ℃)所制备样品的测量结果表明,较低温度下生长的AlN缓冲层有利于制备高质量的ZnO外延层薄膜,其中AlN缓冲层生长温度为100 ℃时外延生长ZnO薄膜晶体质量最好.     

缓冲层对InSb/GaAs薄膜质量的影响

InSb是制作3~5μm红外探测器的重要材料。在GaAs衬底上外延生长InSb,存在的主要问题在于两种材料间14.6%的晶格失配度,会引入较大的表面粗糙度以及位错密度,使外延材料的结构和电学性能均会受到不同程度的影响。通过系列实验,研究了在生长过程中缓冲层对薄膜质量的影响。利用高能电子衍射仪(RHHEED)得到了合适的生长速率和Ⅴ/Ⅲ比,研究了异质外延InSb薄膜生长中低温InSb缓冲层对材料生长质量以及不同外延厚度对材料电学性质的影响。采用原子力显微镜(AFM)、透射电子显微镜(TEM)、X射线双晶衍射(DCXRD)等方法研究了InSb/GaAs薄膜的表面形貌、界面特性以及结晶质量。通过生长合适厚度的缓冲层,获得了室温下DCXRD半高峰宽为172″,77 K下迁移率为64300 cm²·V^-1·s^-1的InSb外延层。     

Zn_（1－x）Mg_xS_ySe_（1－y）四元半导体合金的拉曼散射光谱研究

用分子束外延方法在ＧａＡｓ（１００）衬底上生长了Ｚｎ１－ｘＭｇｘＳｙＳｅ１－ｙ四元半导体合金薄膜．用Ｘ－射线衍射方法确定了外延层的结构和晶格常数．测量了这些样品在平行和垂直两种不同几何配置下的拉曼散射光谱并对其特性做了研究。从实验上观察到了四类不同的晶格振动模：类ＺｎＳｅ的ＴＯ和ＬＯ模以及类ＺｎＳ和类ＭｇＳ的ＬＯ模，实验发现：在ＺｎＳｅ和ＺｎＳＳｅ中加入Ｍｇ使得类ＺｎＳｅ的ＴＯ和ＬＯ模的振动频率下降；同时，也使类ＺｎＳ模的频率随Ｓ的增加率减小。     

双层介电系统的Raman散射——ZnSe/玻璃和ZnSe/GaAs的表面声子模

本文实验观测了双层介电系统ZnSe/玻璃和ZnSe/GaAs的表面声子模,并利用极化场边界条件对上述体系的表面声子频率进行了计算。实验结果与计算结果符合得比较满意。     

Raman-spectroscopy study of PbTiO3 thin films grown on Si substrates by metalorganic chemical vapor deposition

Raman spectra have been investigated in PbTiO₃ thin films grown on Si by metalorganic chemical vapor deposition. A large grazing-angle scattering technique was taken to measure the temperature dependence of Raman spectra below room temperature. All Raman modes in the thin films are assigned and compared with those in the bulk single crystal, a newA ₁(TO) soft mode at 104 cm^–1 was recorded which satisfies the Curie-Weiss relation ² =A(T _c –T). Intensities of theA ₁(1TO) andE(1TO) modes were anomalously strengthened with increasing temperature. Raman modes for the thin films exhibit remarkable frequency downshift and upshift which is related to the effect of internal stress.     

(002)取向AIN薄膜的Raman光谱

（００２）取向ＡＩＮ薄膜的Ｒａｍａｎ光谱赵永年王波何志罗微邹广田（吉林大学超硬材料国家重点实验室长春１３００２３）ＲａｍａｎＳｐｅｃｔｒａｏｆＡＩＮＦｉｌｍｓＯｒｉｅｎｔｅｄｉｎ（００２）ＺｈａｏＹｏｎｇｎｉａｎ，ＷａｎｇＢｏ，ＨｅＺｈｉ，ＬｕｏＷｅ...     

Temperature dependence of the optical properties of ZnSe films deposited on quartz substrate

ZnSe thin films were deposited by pulsed laser ablation on quartz substrate. The films were investigated by different characterization techniques, such as X-ray diffraction, Raman microspectroscopy, absorption, reflectivity, and photoluminescence spectroscopy. The XRD analysis showed the formation of cubic phase polycrystalline films. The Raman spectra confirmed the formation of ZnSe by the presence of TO and LO peaks at 202 cm^-1 and 252 cm^-1, respectively. The analysis of absorption and reflectivity measurements permits evaluation of the band gap and excitonic energy at low temperature and the temperature dependence of the energy gap. The photoluminescence measurements indicated the possibility of obtaining intrinsic band-band radiative emission up to room temperature. PACS 52.38.Mf; 78.55.-m; 78.55.Et     

Infrared and Raman spectroscopies of InP/II–VI core-shell nanoparticles

We use infrared (IR) and Raman spectroscopies to investigate the optically active phonon modes in InP nanoparticles and InP/II–VI core-shell nanoparticles fabricated by similar colloidal chemistry methods. The IR transmission spectra of several InP nanoparticle samples exhibit a common absorption feature, which we assign to the Fröhlich mode. The Raman results for the same samples show transverse and longitudinal optical phonon peaks, and scattering strength in between due to surface optical (SO) modes. Infrared spectra of the InP/ZnSe core-shell nanoparticles () exhibit three absorption features, one due to the InP core, and the others associated with the ZnSe shell layer. Raman measurements (12–292 K) also show three phonon-related peaks, whose intensities vary sharply with temperature. The frequencies of the IR and Raman lines are in approximate accord with dielectric continuum theory.     

ZnSe-ZnS应变超晶格的Raman散射

本文报导了Znse—ZnS应变超晶格的Raman光学声子谱.我们观测到,随着应变大小的改变,ZnSe和ZnS的纵向光学声子发生频移.ZnSe层中纵向光学声子可发生较大的蓝移,也可发生较小的红移;ZnS层中的纵向光学声子发生较大的红移.这些现象为“应变场下的光学模理论”所解释.文中还报导了在波数为110cm-1处观测到一很强的散射峰,并把它归结为超晶格表面层单斜Se所引起的散射;在其它地方还观测到非晶态Se、三角Se引起的散射峰.     

Hydrogenation effect on electrical,optical and magnetic properties of ZnSe/Co bilayer DMS thin films

This paper reports ZnSe/Co bilayer diluted magnetic semiconductor thin films have been prepared by using thermal evaporation technique. The bilayer DMS thin films were hydrogenated at different pressures (15–45 psi) for a constant time of 30 min. Before and after hydrogenations of these bilayer thin films the electrical, optical and magnetic properties have been investigated. Electrical resistivity and optical band gap were found to be increased with respect to hydrogenation pressure. X-ray diffraction (XRD) and magnetic measurements confirmed the formation of DMS ZnSe/Co bilayer DMS thin films. Raman spectra show the presence of hydrogen in these thin films. Surface topography study of as-grown, annealed and hydrogenated ZnSe/Co bilayer thin films indicates uniform deposition, mixing of layers and increment in roughness at the surface due to hydrogen passivation effect respectively.     

Raman Spectrum Study on the Doping Effect in LiNbO3: MgO Crystals

Raman spectra of LiNbO₃: MgO crystals have been obtained and compared with Raman spectra of pure LiNbO₃ crystals. For both of the two kinds of Raman active modes (4A₁+9E), no changes of the numbers, frequency-shifts, and relative intensities of the Raman spectral lines are found. However, it is observed that some modes coupled to each other at room temperature. The observed modes coupling phenomena, disappeared at low temperature. It is shown from these results that the Raman spectral lines of A₁ (TO) and E (TO) vibrational modes are mainly determined by the (NbO₆) oxygen octahedra characteristic groups of LiNbO₃ crystals.