β-Ga_2O_3薄膜的分子束外延生长及其紫外光敏特性研究

采用分子束外延(MBE)方法在Al2O3(0001)基片上生长了β-Ga2O3薄膜,利用XRD、SEM和AFM对薄膜的结构和形貌特性进行了表征。制作了基于β-Ga2O3薄膜的金属-半导体-金属(MSM)结构紫外探测器并对其进行了电学特性测试,结果表明:在20 V偏压下,器件的暗电流为8 nA;在波长为254 nm、光照强度为13×10–6W/cm2的紫外光照射下,器件的光电流为624 nA;器件的光电流与暗电流比值为78,光响应度达360 A/W,表现出明显的日盲紫外光响应特性。     

锐钛矿TiO2薄膜的制备及其紫外光电导性能研究

采用直流反应磁控溅射的方法, 溅射高纯钛靶在ITO石英衬底上制备了TiO2薄膜.用Raman光谱、AFM和紫外-可见光分光光度计分别测试了TiO2薄膜的结构、表面形貌和紫外-可见光吸收谱,研究了工艺因素中溅射气压、氧氩比和退火温度对薄膜结构的影响.采用C(胶)/TiO2/ITO三层结构研究了锐钛矿TiO2薄膜的紫外光响应.实验结果表明:较低的溅射气压、合适的氧氩比和较高的退火温度有利于锐钛矿TiO2薄膜的结晶.在2V的偏压下,锐钛矿TiO2薄膜的紫外光响应上升弛豫时间约为3s,稳定光电流可达到2.1mA,对紫外光的灵敏性和稳定的光响应表明TiO2薄膜有可能成为一种新的紫外光探测器材料.     

ZnO薄膜紫外探测器的光电性质

采用直流反应磁控溅射的方法制备ZnO薄膜, 用X射线衍射仪(XRD)、扫描电镜(SEM)和紫外-可见光谱仪(UV-Vis)分别表征ZnO薄膜的晶体结构和表面形貌等特征。并用此材料制备Au/ZnO/Au金属-半导体-金属(MSM)结构光电导型ZnO薄膜紫外光探测器。实验结果表明, ZnO探测器在360 nm出现明显光响应,其光电流为2.5 mA, 在5 V偏置电压下暗电流为250 μA; ZnO紫外探测器在250～380 nm的紫外波段, 探测器有很明显的光响应, 且光电流响应比较平坦; 在380～430 nm区域, 光响应明显下降; 其光响应的上升与下降弛豫时间分别为20 s与80 s。从光谱响应图中可以看出紫外(360 nm)比可见区(450 nm)的光响应高出3个数量级, 薄膜表面存在的缺陷(如氧空位)在ZnO紫外探测器的光电效应中有重要作用。     

电子束沉积生长高迁移率IMO透明导电薄膜的研究

研究了利用电子束反应蒸发技术梯度速率生长高迁移率In2O3:Mo(IMO)薄膜的微观结构、光学和电学性能。高纯度In2O3:MoO3陶瓷靶和O2作为源材料。首先,利用低沉积速率(约0.01nm/s)生长一层厚度约为30nm的IMO薄膜,作为缓冲层,其次,提高生长速率至0.04nm/s,高速率生长IMO薄膜,薄膜厚度约50nm。典型薄膜电阻率ρ约为2.5×10-4Ωcm,方块电阻Rs约为22.5Ω,载流子浓度n～5.8×1020cm-3,电子迁移率μ约为47.1cm2V-1s-1,可见光和近红外区域平均透过率约为80%。获得的IMO薄膜光电性能和直接利用低速率生长的薄膜特性相当或更好,并且极大地降低了薄膜生长时间。     

Al掺杂ZnO紫外探测器的快速响应技术

通过交变电场下的紫外光响应测试,观察到ZnO基薄膜在254 nm紫外光激发下的慢响应现象,并测量了响应时间常数。为提高ZnO基薄膜紫外探测器的性能,采用磁控溅射法,制备了纯ZnO薄膜和掺Al浓度为10 at.%(原子比例)的ZnO薄膜紫外探测器,测量了样品的频率特性曲线。结果表明,Al掺杂能有效地抑制ZnO薄膜的慢响应,实现探测器对紫外光的响应时间常数τ<25μs的快速响应。     

硅基外延锗金属-半导体-金属光电探测器及其特性分析

利用超高真空化学汽相淀积(UHV/CVD)设备,以低温下生长的薄的Si1-xGex和Ge作为缓冲层,在Si(100)衬底上外延出表面平整(粗糙度＜1 nm)、位错密度低(＜5×105 cm-2、厚度约为500 nm的高质量纯Ge层.Ge层受到由于Si和Ge热膨胀系数不同引入的张应变,应变大小约为0.2%.以外延的Ge层为吸收区、在硅基上制备了台面面积为195×150 μm2的金属-半导体-金属(MSM)光电探测器.在-1 V偏压下,暗电流为2.4×10-7 A;在零偏压下,光响应波长范围扩展到1.6 μm以上.     

Cu掺杂TiO2薄膜的超亲水性与电化学特性研究

通过溶胶-凝胶方法分别在ITO和玻璃表面制备了TiO2:Cu薄膜,研究了TiO2:Cu薄膜在365nm的紫外光照射下的光致超亲水性及在Na2SO4电解溶液中的循环伏安行为,研究了掺杂浓度对薄膜的光致超亲水性的影响.结果表明,在紫外光的照射下,TiO2:Cu薄膜电极表现光电化学过程及光致超亲水性,原因在于在紫外光照射下TiO2:Cu薄膜的超亲水性变化与产生TiO3 的过程引起的表面微观结构变化存在一定的内在联系.与纯TiO2薄膜相比,掺入适量Cu(Cu/Ti摩尔比:0.002)后的薄膜具有更好的光致超亲水性和较强的峰电流.经1h的紫外光照射后,该薄膜的水接触角接近于O°,峰电流达1.754μA.     

高速Ga0.47In0.53AsMISIM光探测器

用于光纤系统高速光探测器,对未来的高速系统是十分重要的,这种光探测器必须能够与电子元件集成在一起。作者介绍了一种新技术,能够制作达到上述要求的金属-绝缘体-半导体-绝缘体-金属MISIM光探测器。这种器件采用增强肖特基势垒层的Langmaiz-Btodgett(L-B)薄膜。在低偏压下(5V),获得的宽带线性响应达13GHZ,外部响应约为0.9-A/W,击穿电压为1.5V,暗电流2μA。经分析,瞬间响应的增益约为2,尾随脉冲约为5％,所需的偏压和器件工艺与集成式接收器相同。     

热氧化法制备ZnO薄膜及其紫外探测特性研究

采用电子束蒸发方法在玻璃衬底上沉积了Zn薄膜,然后在空气中进行了400 ℃至550 ℃加热退火处理,并基于金属-半导体-金属(MSM)平面式结构,制备了ZnO光电导型紫外探测器.实验发现:退火后的薄膜样品表面出现了ZnO纳米线,纵横比在300～1000间;探测器的响应峰值波长约为360 nm,紫外区光响应度是可见区的5倍以上;360 nm紫外光照射的瞬态响应符合e指数变化规律,e指数曲线拟合所得到的驰豫时间常数反映了这个过程中的时间积累.     

IWO缓冲层对MOCVD-ZnO:B薄膜性能的影响研究

金属有机化学气相沉积(MOCVD)技术生长的绒面ZnO透明导电(ZnO-TCO)薄膜应用于Si基薄膜太阳电池上能够形成"陷光结构",以提高薄膜太阳电池效率和稳定性。本文将电子束反应蒸发技术生长的掺W的In2O3(In2O3:W,(IWO)薄膜作为缓冲层,应用于MOCVD-ZnO:B薄膜与玻璃之间,可促进ZnO:B薄膜的生长,并且有效提升薄膜的光散射特性。当IWO缓冲层厚度为20nm时,获得的IWO/ZnO:B薄膜的电阻率为2.07×10-3Ω.cm,迁移率为20.9cm2.V-1.s-1,载流子浓度为1.44×1020 cm-3;同时,薄膜具有的透过率大于85%,且在550nm处绒度较ZnO:B薄膜提高了约9.5%,在800nm处绒度较ZnO:B薄膜提高了约4.5%。     

Y1Ba2Cu3O7-x半导体薄膜的红外热辐射响应研究

采用直流磁控溅射后退火法制备了Y1Ba2Cu3O7-x/Si和Y1Ba2Cu3O7-x/ZrO2/SiO2两种半导体薄膜，对该薄膜进行了红外热辐射响应特性研究。采用X射线衍射、电阻温度系数法、喇曼散射表征手段对薄膜的显段结构进行了详细分析。结果表明，有过渡层的Y1Ba2Cu3O7-x半导体薄膜均匀性好，信噪比高，在红外波段和亚毫米波段甚至毫米波段都有良好的热辐射响应，适于制做非制冷探测器的敏感元。     

Analysis of the properties of germanium/zinc silicate film growth through a simple thermal evaporation technique for hydrogen gas sensing and deep UV photodetector application

Germanium/zinc silicate (Ge/Zn₂SiO₄) thin films were produced in a high-temperature horizontal tube furnace. Structural and optical properties of thin films were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Room temperature Raman spectra were also obtained. Nickel (Ni) metal–semiconductor–metal (MSM) contacts were deposited on the Ge/Zn₂SiO₄ thin film by evaporating Ni using an appropriate MSM mask. Corresponding current–voltage characteristics of the Schottky diodes were recorded before and after (2%) hydrogen (H₂) gas exposure with different flow rates. The respectable response and sensitivity of the MSM to H₂ gas heighten the potential interest in future gas sensor devices. The strong photoelectric properties of the MSM in the deep ultraviolet demonstrate that the film contributes to photosensitivity. Therefore, Ge/Zn₂SiO₄ films are potential photodetectors in short wavelength applications.     

sol-gel法制备ZnO薄膜压敏电阻

利用sol-gel法在镀有Au底电极的单晶硅片上,制备掺有Bi2O3、Co2O3、Cr2O3和MnO2的ZnO薄膜压敏电阻。薄膜由旋涂法制备,并在300℃下预处理、600℃退火。制得的ZnO薄膜结晶良好。膜厚约为1μm,ZnO薄膜压敏电阻的非线性系数为15.1,压敏电压为3.037 V,漏电流为43.25μA。     

Ge2Sb2Te5的电化学特性及化学机械抛光

从电化学角度研究了Ge2Sb2Te5薄膜在化学机械抛光液中的作用，以及不同的pH值和H2O2浓度下的电化学特性. 采用Solartron SI1287电化学设备测试了Ge2Sb2Te5薄膜在溶液中的开路电位和动电位扫描. 开路电位结果表明：Ge2Sb2Te5在pH值为10的抛光液中表现出钝化行为；而抛光液的pH值为11时，开始向活化转变；当pH值为12时，薄膜处于活化状态. 在动电位扫描过程中，不同的pH值和H2O2浓度下，薄膜的扫描曲线形状相似，表明薄膜腐蚀具有相同的反应机理. 自制碱性抛光液，对Ge2Sb2Te5薄膜进行化学机械抛光，用SEM和EDS对抛光后的结构进行分析. 结果表明，通过CMP实现了Ge2Sb2Te5填充结构.     

Solution‐Processed Self‐Powered Transparent Ultraviolet Photodetectors with Ultrafast Response Speed for High‐Performance Communication System

Transparent ultraviolet (UV) photodetectors are an essential component of next‐generation “see‐through” electronics. However, the current photodetectors often suffer from relatively slow response speeds and high driving voltages. Here, all‐solution‐processed UV photodetectors are reported that are facilely prepared from environmentally friendly and abundant materials. The UV photodetectors are composed of a titanium dioxide thin film as the photosensitive layer sandwiched between two different transparent electrodes to form asymmetric Schottky junctions. The photodetector with high optical transparency can operate at zero bias because of spontaneous separation of photogenerated electron–hole pairs by the built‐in electric field. The resulting self‐powered photodetector displays high sensitivity to broadband UV light (200–400 nm). In particular, an ultrafast response speed up to 44 ns is obtained, representing a significant improvement over those of the conventional transparent photodetectors. Moreover, the photodetector has been successfully applied, for the first time, in a UV communication system as the self‐powered signal receiver. This work uniquely combines the features of high optical transparency and self‐power ability into UV photodetectors and would enable a broad range of optoelectronic applications.     

新型VO_2相变薄膜的制备

采用离子束溅射和退火工艺制备了一种新的相变型薄膜VO2。此种薄膜的方块电阻为120～148kΩ,电阻-温度关系曲线显示该薄膜的相变温度接近室温。SEM分析表明,所制备的薄膜致密均匀。样品的明场透射电子显微图像显示,制备的薄膜是多晶薄膜,晶粒尺寸达到纳米数量级。XRD分析表明,该薄膜的成分中除了含有VO2外,还含有V2O5,说明该工艺制备的是含有VO2的混合物,而不是纯VO2薄膜。     

Normal-incidence mid-infrared Ge quantum-dot photodetector

Mid-infrared photodetectors were demonstrated by using molecular-beam epitaxy (MBE)-grown self-assembled Ge quantum dots (QDs). The response wavelength ranged from 2.2 μm to 3.1 μm and peaked at 2.8 μm. The peak response wavelengths shifted to 2.9 μm and 3.5 μm after thermal annealing at 700°C and 900°C for 5 min, respectively. Normal-incidence detection was confirmed, and the mechanism of a Ge QD photodetector was discussed. Calculations showed the key parameters determining response wavelength of the Ge QD infrared photodetector, which agreed with experimental results.     

NH3等离子体钝化对Al2O3/SiGe界面的影响

研究了不同条件的非原位NH_3等离子体钝化对Al_2O_3/SiGe/Si结构界面组分的影响。在p型Si(100)衬底上外延一层30 nm厚的应变Si_0.7Ge_0.3,采用双层Al_2O_3结构,第一层1 nm厚的Al_2O_3薄膜为保护层,之后使用非原位NH_3等离子体分别在300和400℃下对Al_2O_3/SiGe界面进行不同时间和功率的钝化处理,形成硅氮化物(SiN_xO_y)和锗氮化物(GeN_xO_y)的界面层。通过X射线光电子能谱(XPS)分析表面的物质成分,结果表明NH_3等离子体钝化在界面处存在选择性氮化,更倾向于与Si结合从而抑制Ge形成高价态,这种选择性会随着时间的增加、功率的增高和温度的升高变得更加明显。     

Impact of Local Strain From Selective Epitaxial Germanium With Thin Si/SiGe Buffer on High-Performance p-i-n Photodetectors With a Low Thermal Budget

This letter reports on the impact of selective epitaxial germanium, specifically its local strain effects, on high-performance p-i-n photodetectors for near-infrared applications. By combining a thin compliant Si epitaxial layer (~6 nm) with SiGe buffer (10-15 nm), we demonstrated a high-quality Ge film (~150 nm) prepared by two-step growth. Without using high-temperature cyclic anneal, Ge films with smooth surface (root mean square = ~ 0.67 nm) and low dislocation density (4 x 10⁶ cm^-2) have been produced. The Si buffer locally enhances the tensile strain (epsiv = 0.63%) in Ge while slightly suppressing the dark current by half to 0.12 muA (with circular ring area = 1230 mum² and spacing = 2 mum). A lateral p-i-n Ge photodetector has been demonstrated with enhanced photoresponse of ~190 mA/W at 1520 nm and a 3-dB bandwidth of 5.2 GHz at 1 V.