GaAlAs／GaAs发光管中深能级与暗缺陷关系

本文用DLTS和瞬态单电容技术研究了液相外延生长的GaAlAs/GaAs有源层掺Si器件的深能级，用红外显微镜测量了近场EL图像，研究了深能级及暗结构缺陷的器件的影响及它们间的关系。     

砷化镓气相外延中Zn的行为和微光材料的制备

在Ga-AsCl_3-H_2系统中用金属Zn为掺杂剂,研究了气相外延GaAs时Zn的掺入和行为。GaAs中Zn的分配系数和空穴浓度分别为10和大于10~(20)cm~(-3),它们都比掺Cd的GaAs大2—3个数量级。这保证了用以制备光阴极材料所需的高空穴浓度的P-GaAs。结合掺Zn和掺s,已重复制得界面良好的P-n结构材料。     

磷扩散氧化锌单晶的性质

分别在550和800℃对CVT方法生长的非掺ZnO单晶进行闭管磷扩散. 通过Hall测试、X射线光电子谱（XPS) 、光致发光（PL）以及喇曼散射对扩散后的样品进行测试分析. 发现扩散掺杂后的ZnO单晶仍显示n型导电性,自由电子浓度比非掺样品增高,在800℃扩散后尤为明显. PL测试结果表明,掺杂样品在420~550nm范围的可见光发射与缺陷有关. XPS测试表明:在550℃掺杂,P原子更易代替Zn位;在800℃扩散时,P未占据Zn位,而似乎占据了O位. 最终在磷扩散后的ZnO单晶中形成了高浓度的浅施主缺陷,造成了自由电子的显著增加.     

磷扩散氧化锌单晶的性质

分别在550和800℃对CVT方法生长的非掺ZnO单品进行闭管磷扩散.通过Hall测试、X射线光电子谱(XPS)、光致发光(PL)以及喇曼散射对扩散后的样品进行测试分析.发现扩散掺杂后的ZnO单晶仍显示n型导电性,自由电子浓度比非掺样品增高,在800℃扩散后尤为明显.PL测试结果表明,掺杂样品在420～550nm范围的可见光发射与缺陷有关.XPS测试表明:在550℃掺杂,P原子更易代替Zn位;在800℃扩散时,P未占据Zn位,而似乎占据了O位.最终在磷扩散后的ZnO单晶中形成了高浓度的浅施主缺陷,造成了自由电子的显著增加.     

对GaP绿色发光材料的缺陷观察及分析

用高倍金相显微镜及红外显微镜,对掺杂为Te、晶面是(111)的n型GaP单晶及掺N、Zn液相外延生长的P型GaP外延层,进行了缺陷及杂质偏析的观察;从而分析了导致偏析的原因及缺陷形成和增殖的机理。     

掺Sb的ZnO单晶的缺陷和性质研究

采用化学气相传输法生长了掺Sb的ZnO体单晶,生长温度为950℃.与非掺ZnO单品相比,掺Sb后ZnO单晶仍为n型,其自由电子浓度明显升高.x射线光电子能谱(XPS)测量结果表明.掺人的Sb在ZnO单晶中可能占据了Zn位,或处于间隙化置,形成了施主.利用光致发光谱(PL)测量发现掺Sb后ZnO单晶发出蓝光,该蓝色荧光与浅施主有关.这些结果表明在高温生长条件下,掺Sb后ZnO单晶中产生了高浓度的施主缺陷,因而难以获得P型材料.     

MOCVD AlGaAs/GaAs HBT材料生长中基区、发射区结偏位的分析与控制

分析了MOCVDAlGaAs/GaAsHBT外延材料生长中基区、发射区异质结界面与P N结界面产生偏离的原因 ,计算了外延生长参数对结偏离的影响 ,得到了对于C、Mg及Zn作为P型掺杂剂时 ,使得结偏位为 0时所需生长的GaAsspace层厚度 ,它们分别为 1～ 1.5nm、3～ 4nm及 12～ 15nm。计算与器件研制结果基本相符。     

原生掺Si砷化镓单晶微缺陷的研究

本文采用TEM和阳极腐蚀法、化学腐蚀法,研究了原生掺Si砷化镓单晶中的微缺陷及其行为;并确定了这些缺陷的性质.结果表明,在掺Si砷化镓晶体中,当其电子浓度n≥3 ×10~(15)cm~(-3)时,微缺陷才出现.从微观完整性言,Si是GaAs的N型掺杂剂中较好的一种.     

应用SEM和V-I特性研究1.3μmInGaAsP/InP DH激光器中掺杂的影响

本文说明用 SEM和V-I特性法研究 1.3μm InGaAsP/InP DH激光器中掺杂对 PN结位置及 PN结性质的影响.认为用 Zn作P型掺杂剂的 InGaAsP/InP DH 激光器中,由于Zn在InGaAsP和InP晶体中的快扩散及外延生长期间Zn蒸气沾污是PN结偏位的主要原因.施主和受主掺杂的高浓度会产生隧道型 PN 结. 因此在研制激光器的工艺中,控制Zn的沾污及掺杂剂的浓度是非常重要的.     

在Si~ 离子注入GaAs的N~ 层上制作欧姆接触的研究

近几年来,用离子注入的方法,直接在半绝缘GaAs衬底上注入Se、S、Si Te等施主型掺杂剂形成N型有源层,用以制造GaAs MES FET和GaAs集成电路的发展异常迅速。这不仅仅是因为离子注入工艺操作简单、可控性好,大面积均匀,无内界面等优点,更重要的是,它具有类似于硅工艺的平面型结构和大大地降低了成本。要使GaAs器件及其集成电路的应用象Si那样广泛和普及,必须具备廉价的GaAs材料和类似于硅平面工艺那样简便而成熟的制造技术。显然,半绝缘的GaAs衬底和离子注入技术则是实现这一目标的有效途径。然而,由于离子注入固有的特点,相对说来,要求半绝缘GaAs衬底必须具有1) 良好的热稳定性,在850℃以上,恒温1小时,其半绝缘性能保持不变。2) 低的掺Cr浓度,最好是不掺Cr的高纯衬底。3) 晶格比较完美、缺陷密度小于     

Observation and study on the dark defects in InGaAsP/InP double-heterostructure leds

 The defects in lnGaAsP/InP DH LEDs are observed with an infrared line scanner.The dark structure appears before aging and it exists mainly in the form of dark spot defect.The effect of the variety and concentration of the doping for p-InP confining layers on the dark defects is studied.The results show that the percentage of devices with dark defects is much lower for Mg or In-Zn doped devices than for Zn doped devices.It is believed that Zn is one of the important origin for the formation of dark defects.The growth rate of dark defects is studied both at room temperature and at 70—85℃.The results show that after agin for 15000 h at room temperature there are no dark defects newly appeared.But after aging for 2000 h at 70—85℃ some devices show newly formed dark structure with very slow growth rate.     

室温固相化学法制备掺杂纳米氧化锌

为制备分散性良好的掺杂氧化锌纳米粉体,以硝酸锌、碳酸氢铵及掺杂离子的盐为原料,通过室温固相化学反应先制备出掺杂前驱物——碳酸盐。根据DSC-TGA分析结果,将其在275℃分解2h,得到掺杂氧化锌粉体。采用激光粒度分析、BET、XRD、SEM对产物的粒度、物相组成、颗粒形貌等进行了表征。结果表明:所制备的掺杂氧化锌粉体呈粒状,粒度分布均匀,晶粒度为52.35nm。     

非故意掺杂吸收层InP/InGaAs异质结探测器研究

为了获得低噪声铟镓砷（InGaAs）焦平面,需要采用高质量的非故意掺杂InGaAs（u-InGaAs）吸收层进行探测器的制备。采用闭管扩散方式,实现了Zn元素在u-InGaAs吸收层晶格匹配InP/In_0.53Ga_0.47As异质结构材料中的P型掺杂,利用扫描电容显微技术(SCM)对Zn在材料中的扩散过程进行了研究,结果表明,随着扩散温度和时间增加,p-n结结深显著增加,u-InGaAs吸收层材料的扩散界面相比较高吸收层浓度材料（5×1016 cm?3）趋于缓变。根据实验结果计算了530 ℃下Zn在InP中的扩散系数为1.27×10?12 cm2/s。采用微波光电导衰退法(μ-PCD)提取了InGaAs吸收层的少子寿命为5.2 μs。采用激光诱导电流技术(LBIC)研究了室温下u-InGaAs吸收层器件的光响应分布,结果表明:有效光敏面积显著增大,对实验数据的拟合求出了少子扩散长度L_D为63 μm,与理论计算基本一致。采用u-InGaAs吸收层研制的器件在室温(296 K)下暗电流密度为7.9 nA/cm2,变温测试得到激活能E_a为0.66 eV,通过拟合器件的暗电流成分,得到器件的吸收层少子寿命τ_p约为5.11 μs,与微波光电导衰退法测得的少子寿命基本一致。     

Influences of annealing temperature on structural,magnetic and optical properties of Zn0.98V0.02O nanoparticles

The Zn_0.98V_0.02O nanoparticles were synthesized by the sol–gel method. The relationship between the annealing temperature (600 °C, 700 °C and 800 °C) and the structural, magnetic and optical properties of the obtained samples was studied. The results showed that Zn ions were partially substituted by V ions. The V doped ZnO nanoparticles annealed at 600 °C and 700 °C were single phase wurtize ZnO structure and they were ferromagnetic at room temperature. On the contrary, the sample annealed at 800 °C had a secondary phase of Zn₃V₃O₈. Therefore it was not saturated even in the field of 10,000 Oe due to the coexistence of ferromagnetic and paramagnetic materials. Photoluminescence results indicated that defects probably were the origin of ferromagnetism in V doped ZnO.     

MnO_2掺杂量对BaCo_(0.05)Co_(0.1)Bi_(0.85)O_3厚膜NTCR电性能影响

以新型BaCo0.05Co0.1Bi0.85O3材料为基体,掺杂不同摩尔分数x(MnO2),在840℃下烧结4h制备了NTC厚膜电阻。借助XRD、SEM和直流阻温特性测试仪,研究x(MnO2)对电阻相组成、微结构及电性能的影响。结果表明:所得的NTC厚膜热敏电阻主要物相为具有钙钛矿结构的BaCo0.05Co0.1Bi0.85O3,且表面致密。当x(MnO2)超过5%时,有新相BaMnO3开始沿晶界析出,获得小尺寸晶粒;厚膜电阻的室温电阻率ρ25及B25/85值随x(MnO2)增加而升高;当x(MnO2)为10%时,ρ25从初始的13.5?·mm升高为810.0?·mm,B25/85值从600K升高到2049K。     

Minority carrier diffusion length in liquid epitaxial GaP

Using a Schottky diode photocurrent technique, investigations have been made of the room temperature value of minority carrier diffusion length in liquid epitaxial GaP grown on both (111) and (100) oriented pulled GaP substrates. Results are presented for undoped layers and layers doped separately with S, S and N, Te, Zn, and Zn and O, to cover a range of impurity concentration in the GaP. The measured values of minority carrier diffusion length are found to depend on the concentration of the dominant impurity and, for the undoped and Zn doped layers, also on the growth orientation of the substrate. From the dependence of the minority carrier diffusion length on majority carrier concentration we infer the dominant room temperature recombination process in the layers. In our undoped layers this process is believed to correspond to recombination via residual Si substituted on P sites. In Te, S, Zn, and Zn, O doped layers the dominant recombination mechanism can be attributed to a non-radiative band-band Auger process, although in the case of the Zn, O doped layers a competing recombination process is observed which is believed to correspond to recombination via centres formed by unpaired O and Zn defects. The lifetime for this competing process is predicted to be sensitive to annealing.     

Mn掺杂对SrBiFeO陶瓷NTC特性的影响

以Bi2O3,Fe2O3,MnO2和SrCO3为主要原料,采用传统固相法制备出具有负温度系数(NTC)特性的SrBiFeMnO陶瓷。研究了该陶瓷的物相结构、断面形貌及电性能。结果表明:试样的室温电阻率ρ25和热敏电阻特性常数B25/85随着x(Mn)的增加均呈现先增大后减小的趋势。在25～200℃的测试温区内,x(Mn)为0.1时,掺杂的SrBiFeO陶瓷材料的电阻率-温度特性呈现良好的线性关系;x(Mn)为0.5时,掺杂SrBiFeO陶瓷材料具有较好的NTC特性,其ρ25为145Ω.cm,B25/85为2950K。     

Reliability of InGaAs/InP long-wavelength p-i-n photodiodes passivated with polyimide thin film

The long-term reliability of InGaAs/InP p-i-n photodiodes passivated with polyimide thin film was studied through a room temperature life test and through thermally accelerated life tests. No degradation in dark current was observed in a room temperature life test at a reverse bias of -15 V after aging for 7000 h. However, the dark current increased gradually in the accelerated life tests at 110°C, 130°C, and 150°C. It was confirmed that the activation energy of degradation in dark current was 0.85 eV and the average lifetime was estimated to be 10⁷h at room temperature. The dark current recovered in high temperature storage tests. The phenomenon of degradation and recovery was qualitatively explained by a model of accumulation and diffusion of mobile ions at a junction perimeter.     

Long-wave (10 μm) infrared light emitting diode device performance

Electroluminescence in the range of 6–12 μm is observed from an Sb-based type-II interband quantum cascade structure. The LED structure has 30 active/injection periods. We have studied both top-emitting and flip-chip mount bottom emitting LED devices. For room temperature operation, an increase, saturation and decrease in light output occur at successively higher injection currents. An increase of about 10 times in light output occurs when device is operated at 77 K compared to room temperature operation. This increase is attributed to reduced Auger non-radiative recombination at lower temperatures. The peak-emission wavelengths at room temperature and 80 K operation are 7 and 10 μm, respectively. These devices can be used for high-temperature simulation in an infrared scene generation experiment.     

Effect of nano Al2O3 particles doping on electromigration and mechanical properties of Sn–58Bi solder joints

In the present study, the effect of Al₂O₃ nanoparticles on performances of Sn–58Bi solder were investigated in aspects of electro-migratio, shear strength and microhardness. The experimental results show that the Al₂O₃ nanoparticles significantly improved microstructure and mechanical performances of solder joints. With the addition of 0.5 wt% Al₂O₃, the intermetallic compounds (IMC) reduced from 2.5 μm to 1.27 μm after 288 aging hours at 85 °C. Furthermore, after electromigration test under a current density of 5 × 10³ A/cm² at 85 °C, Bi-rich layers formed at the anode side of both Al₂O₃ doped and plain solder. Moreover, the addition of Al₂O₃ nanoparticles reduced the mean thickness of Bi-rich layer. In addition, the growth rate of the IMC layer of Al₂O₃ doped solder decreased by 8% compared with the plain solder. Besides, the Al₂O₃ doped solder exhibited better performance than plain solder in microhardness after different aging times. While, the addition of Al₂O₃ significantly impeded the degradation of the shear strength of solder joint after aging for 48 and 288 h. Furthermore, it was worth noting that the fracture surface of doped solder showed a typical rough and ductile structure. However, plain solder exhibited a relatively smooth and fragile surface.