利用P-MBE在Si（111）衬底上生长氧化锌薄膜及其光学性质的研究

在Si(111)衬底上利用等离子体辅助分子束外延(P-MBE)生长氧化锌(ZnO)薄膜，研究了在不同衬底生长温度下(350～750℃)制备的ZnO薄膜的结构和光学性质．随着衬底温度的升高，样品的X射线及光致发光的半高宽度都是先变小后变大，衬底温度为550℃样品的结构及光学性质都比较好，这表明550℃为在Si(111)衬底上生长ZnO薄膜的最佳衬底温度；同时，我们还通过550℃样品的变温光致发光谱(81～300K)研究了ZnO薄膜室温紫外发光峰的来源，证明其来源于自由激子发射．     

MgxZn1-xO单晶薄膜和MgZnO/ZnO异质结构的光学性质

报道了利用等离子辅助分子束外延技术,在蓝宝石c平面上外延生长的MgxZn1-xO单晶薄膜以及MgZnO/ZnO异质结构的光学性质.室温下随着Mg浓度增加,合金薄膜样品的发光峰与吸收边均向高能侧移动.研究了样品紫外发光的起因,将MgxZn1-xO合金薄膜的发光归结为束缚激子的复合.在Mg0.08Zn0.92O/ZnO样品中,观察到了分别来自于ZnO层和MgZnO盖层的发光和吸收,并将其归因于来自ZnO层的自由激子和MgZnO盖层的束缚激子发射.     

ZnSe薄膜的激子光谱

采用分子束外延 (MBE)技术 ,在 Ga As(1 0 0 )衬底上生长了厚度从 0 .0 4 5到 1 .4μm的 Zn Se薄膜 .X射线衍射谱证实 ,随着薄膜厚度的增加 ,应变逐步弛豫 .测量了低温下样品的反射谱和光致发光谱 ,观察到轻重空穴的能级在不同应变下的分裂、移动和反转 ,以及激子极化激元 (Po-lariton)对反射谱的影响 .也观察到束缚激子发光随着薄膜厚度的变化规律 :束缚在中性受主杂质上的束缚激子发光 (I1峰 )随着薄膜厚度的增加逐渐变弱直至消失 ,而束缚在中性施主杂质上的束缚激子发光 (I2 峰 )则随着厚度增加逐渐增强 .     

ZnSe薄膜的激子光谱

采用分子束外延(MBE)技术,在GaAs(100)衬底上生长了厚度从O.045到1.4μm的ZnSe薄膜.X射线衍射谱证实,随着薄膜厚度的增加,应变逐步弛豫.测量了低温下样品的反射谱和光致发光谱,观察到轻重空穴的能级在不同应变下的分裂、移动和反转,以及激子极化激元(Polariton)对反射谱的影响.也观察到束缚激子发光随着薄膜厚度的变化规律:束缚在中性受主杂质上的束缚激子发光(I1峰)随着薄膜厚度的增加逐渐变弱直至消失,而束缚在中性施主杂质上的束缚激子发光(I2峰)则随着厚度增加逐渐增强.     

分子束外延生长轻掺杂SiGaAs的光致发光

用具有调制源的分子束外延(MBE)轻掺杂Si生长出GaAs层,并利用低温光致发光测定了它的特性。在光致发光光谱的近带边区观察到了自由激子和束缚激子发射。与杂质有关的发射在光谱特性上发生改变,这可归因于MBE生长中Si分子束的调制发生了变化。在MBE生长过程中,根据提供As源期间内供Si的时间,掺入的硅原子既可成为施主,也可成为受主。通过改变供Si时间,在定域格位上完成了Si掺杂。     

Mg_xZn_(1-x)O单晶薄膜和MgZnO/ZnO异质结构的光学性质

报道了利用等离子辅助分子束外延技术,在蓝宝石c平面上外延生长的Mgx Zn1 - x O单晶薄膜以及Mg Zn O/Zn O异质结构的光学性质.室温下随着Mg浓度增加,合金薄膜样品的发光峰与吸收边均向高能侧移动.研究了样品紫外发光的起因,将Mgx Zn1 - x O合金薄膜的发光归结为束缚激子的复合.在Mg0 .0 8Zn0 .92 O/ Zn O样品中,观察到了分别来自于Zn O层和Mg Zn O盖层的发光和吸收,并将其归因于来自Zn O层的自由激子和Mg Zn O盖层的束缚激子发射     

分子束外延ZnSe/ZnSxSe1-x超晶格光学特性

用分子束外延方法在GaAs(100)衬底上生长了高质量的ZnSe/ZnSxSe1-x(x=0.12)超晶格结构,通过X射线衍射谱和光致发光谱,对其结构特性和光学特性进行了研究.结果表明:在4.4K温度下,超晶格样品显示较强的蓝光发射,主发光峰对应于阱层ZnSe的基态电子到重空穴基态的自由激子跃迁,而且其峰位相对于ZnSe薄膜的自由激子峰有明显蓝移.从理论上分析计算了由应变和量子限制效应引起的自由激子峰位移动,理论和实验结果相吻合.     

MBE生长中缓冲层对InSb/GaAs质量影响的研究

用分子束外延(MBE)方法在GaAs(001)衬底上外延生长了InSb薄膜,并研究了异质外延InSb薄膜生长中缓冲层对材料质量的影响.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272",迁移率为64 300 cm2V-1s-1的InSb外延层.     

分子束外延InAlSb/InSb晶体的质量研究

InAlSb/InSb薄膜材料的晶体质量会直接影响器件的性能。提高薄膜材料的晶体质量可以有效降低器件的暗电流,提高探测率和均匀性等。主要报道了掺铝锑化铟分子束外延技术的初步研究结果。通过采用多种测试方法对InAlSb分子束外延膜的晶体质量进行了分析,找出了影响晶体质量的因素,提高了InAlSb分子束外延的技术水平。实验结果表明,通过优化生长温度、束流比、升降温速率以及退火工艺等生长条件,可以获得高质量的InAlSb分子束外延膜。     

ALE ZnSe单晶薄膜的PL性质

最近,日本茨木电气技术研究所的 T.Yao 等人第一次报导了用原子层外延方法(ALE)生长的不掺杂 ZnSe 单晶薄膜的光致发光性质。光谱显示出很强的激子发射,并由此说明了薄膜质量。单晶薄膜生长所使用的衬底是(100)取向的 GaAs 片。ALE 生长采用 MBE 设备。     

Al薄膜对(002)ZnO/Al/Si结构基片中ZnO薄膜特性影响的实验研究

采用射频磁控溅射法沉积制备了(002)ZnO/A l/Si复合结构。研究了Al薄膜对(002) ZnO/Al/Si复合结构的声表面波器件(SAWD)基片性能影响以及当ZnO 薄膜厚度一定时的Al膜最佳厚度。采用X射线衍射(XRD)对Al和ZnO薄膜进行了结构表征 ,采用 扫描电镜(SEM)对ZnO薄膜进行表面形貌表征,并从薄膜生长机理角度进行了分析。结果 表明,加Al薄膜有利于ZnO薄膜按(002)择优取向生长,并且ZnO 薄膜的结晶性能提高;与(002)ZnO/Si结构基片相比,当Al薄膜 厚为100nm时,(002)ZnO/Al/Si结构中ZnO薄 膜的机电耦合系数提高 了65%。     

透明导电ZnO：Sn薄膜光学和电学性能的研究进展

纯ZnO电阻率高,电学性能不稳定,通过掺杂其他元素提高其光电性能,制备出高质量的ZnO薄膜是实现其应用的关键。文章从制备方法、掺杂浓度和退火等方面综述了Sn掺杂ZnO(ZnO:Sn)薄膜光电性能的研究进展,提出了降低ZnO:Sn薄膜电阻率和提高透光率的有效途径。     

生长时间对氧化锌纳米杆形貌的影响

采用旋涂法在洗净的玻璃衬底上制备了醋酸锌薄膜,并进一步在空气中退火获得了氧化锌(ZnO)薄膜,X射线衍射分析显示退火后获得的ZnO薄膜具有c轴(002)择优取向生长特性.通过水热法以ZnO薄膜为种子层,生长了ZnO纳米杆阵列.研究了在相同的ZnO种子层、前驱液浓度和生长温度条件下,不同生长时间对ZnO纳米杆形貌的影响.扫描电子显微镜照片显示,随着生长时间的增加,ZnO纳米杆阵列的生长具有阶段性规律,并且在经过52h生长后得到了顶端中心被溶解的ZnO纳米管.分析认为该现象和前驱液中Zn2+离子和OH-离子的浓度变化有关,同时也和ZnO的非极性结构有关.     

Synthesis of PbS:ZnO nanotrees by thermal evaporation:morphological, structural and optical properties

Nanotrees ZnO films are synthesized by thermal evaporation method on silicon and glass substrates. PbS powder (5 wt%) is used to obtain the nanostructure and growth modifications. ZnO films are compared with non-doped ones (ZnO film was dense structure without nanotrees). The deposited PbS:ZnO films exhibit polycrystalline orientation using X-ray diffraction (XRD), but the films without doping was less crystalline quality. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the morphology. SEM images (surface and cross section) was confirmed the nanotrees form for doped ZnO film. Energy dispersive X-ray detector (EDX) was used to verify the composition of prepared films. Ultraviolet-visible (UV-Vis), photoluminescence (PL) and micro Raman techniques were used to investigate the optical properties. The PL spectra intensities were found to increase for PbS:ZnO nanotrees. Up to our knowledge, no work has been published regarding the obtained ZnO nanotrees using PbS as dopant via simple thermal evaporation method.     

Improvement in crystal quality of ZnO film on Si substrate by using a homo-buffer layer

ZnO thin films without and with a homo-buffer layer have been prepared on Si(1 1 1) substrates by pulsed laser deposition (PLD) under various conditions. Photoluminescence (PL) measurement indicates that the optical quality of ZnO thin film is dramatically improved by introducing oxygen into the growth chamber. The sample deposited at 60 Pa possesses the best optical properties among the oxygen pressure range studied. X-ray diffraction (XRD) results show that the films directly deposited on Si are of polycrystalline ZnO structures. A low-temperature (500 °C) deposited ZnO buffer layer was used to enhance the crystal quality of the ZnO film. Compared to the film without the buffer layer, the film with the buffer layer exhibits aligned spotty reflection high-energy electron diffraction (RHEED) pattern and stronger near-band-edge emission (NBE) with a smaller full-width at half-maximum (FWHM) of 98 meV. The structural properties of ZnO buffer layers grown at different temperatures were investigated by RHEED patterns. It is suggested that the present characteristics of the ZnO epilayer may be raised further by elevating the growth temperature of buffer layer to 600 °C.     

ZnO薄膜在微光像增强器中的潜在应用

ZnO 薄膜是一种新型的宽带隙透明氧化物薄膜材料,具有优良的物理和化学特性。在微光像增强器中具有多方面的潜在应用。通过对ZnO 材料晶格参数等的研究, 发现可以作为制备高质量GaN 紫外光电阴极的缓冲层。通过对ZnO 能带的研究,发现ZnO 本身还可以独立的作为负电子亲和势光电阴极材料,一旦p 型ZnO 制备获得成功,将更有利于形成负电子亲和势光电阴极。此外,采用蒙特卡罗模拟的方法发现ZnO 薄膜比传统的Al2O3 防离子反馈膜对碳等正离子具有更强的阻挡作用,有可能取代Al2O3 薄膜用于制备三代微光器件防离子反馈膜。ZnO 薄膜还具有较高的二次电子发射系数和适合的电阻率,可以用来制备Si 微通道板打拿极。     

Spray deposited ZnO and Ga doped ZnO based DSSC with bromophenol blue dye as sensitizer: Efficiency analysis through DFT approach

Dye sensitized solar cells based on spray deposited ZnO and Ga doped ZnO (GZO) thin film were fabricated with Bromophenol Blue as the photo sensitizer. XRD results show the hexagonal wurtzite phase of ZnO and GZO thin films with c-axis growth orientation, and the diminished crystalline nature of GZO thin film as the effect of doping. FE-SEM results revealed the morphology induced internal light interaction capability of GZO thin film for better harvesting of photon energy. Photovoltaic studies showed that the DSSC fabricated with GZO thin film has obtained enhanced power conversion efficiency (1%) than the ZnO thin film based DSSC (0.2%), as a result of Ga doping. To investigate the obtained photovoltaic performance of the device, the electronic properties of Bromophenol Blue dye were theoretically analyzed with Density Functional Theory (DFT) study.     

Influences of ZnO buffer layers on the quality of ZnO films synthesized by the metal-organic chemical vapor deposition process

High-quality ZnO thin films were prepared by metal-organic chemical vapor deposition (MOCVD) on a sapphire (a-Al₂O₃) substrate. The synthesis of ZnO films was performed over a substrate temperature of 400–700°C and at chamber pressures of 0.1–10 torr. The structural and optical properties of ZnO films were investigated in terms of deposition conditions, such as substrate temperature, working pressure, and the ratio of Zn precursor (Diethylzinc (DEZn)) to oxygen. The ZnO films, preferentially oriented to 34.42° diffraction because of the (002) plane, were obtained under processing conditions of 700°C and 3 torr. This film shows a full-width at half-maximum (FWHM) of 0.4–0.6°. The results of photoluminescence (PL) spectroscopy also show a strong near band-edge emission at 3.36 eV at 10 K as well as a very weak emission at deep levels around 2.5 eV at room temperature. In addition, we are interested in the introduction of ZnO buffer-layer growth by the sputtering process to reduce lattice mismatch stress. This paper addresses how to advance the crystalline and optical properties of film. The ZnO film grown with the aid of a buffer layer shows a FWHM of 0.06–0.1° in the x-ray diffraction (XRD) pattern. This result indicates that crystalline properties were highly improved by the ZnO buffer layers. The PL spectroscopy data of ZnO film also shows a strong near band-edge emission and very weak deep-level emission similar to films synthesized without a buffer layer. Accordingly, synthesized ZnO films with buffer layers indicate fairly good optical properties and low defect density as well as excellent crystallinity.     

用MOCVD方法在GaAs衬底上低温生长ZnO薄膜

采用二乙基锌(DEZn)和水(H2O)作为生长源,利用金属有机化学气相沉积(MOCVD)的方法,在100～400℃低温范围内,在GaAs(001)衬底上制备了ZnO薄膜.利用X射线衍射(XRD),室温PL,AFM,SEM研究了薄膜的晶体结构特性、发光特性及表面形貌特性.XRD分析表明ZnO薄膜具有很强的c轴取向,(002)峰的FWHM平均值为0.3°.当生长温度达到400℃时从SEM测量结果可以观察到薄膜表面呈六角状结晶.随着生长温度的升高,薄膜的晶粒尺寸变大,结晶质量得到提高但同时表面变粗糙.室温PL测量显示薄膜在370nm附近有强的近带边发射,没有观测到深能级发射峰.     

Analysis of structural, optical and electrical properties of metal/p-ZnO-based Schottky diode

A systematic study of the behaviour of Pd/p-ZnO thin film Schottky diode has been reported. The p-type ZnO thin film with improved stability has been grown on n-type Si by doping ZnO with copper.μSeebeck measurement confirmed the p-type nature of Cu-doped ZnO thin film. The X-ray diffraction spectra of the deposited film revealed polycrystalline nature with preferred growth orientation of (101) of ZnO film. The surface morphological study demonstrated the conformal deposition of a thin film over n-Si wafer. The estimated bandgap of Cu-doped p-type ZnO thin film from ellipsometric measurement turns out to be 3.14 eV at 300 K. The measured electrical parameters of the proposed Pd/p-ZnO Schottky diode have also been validated by the results of numerical simulation obtained by using ATLAS^TM device simulator.