硅表层扩散杂质在CW-CO_2激光辐照后的电激活特性

本文研究了硅中高温扩散硼和磷样品在CW-CO_2激光作用下薄层电阻、载流子面密度、迁移率和表面薄层(450)载流子浓度的变化。经过激光处理后样品表面一薄层载流子浓度超过了杂质的固溶度极限。通过高温热退火和再次激光辐照研究了“超固溶度”的不稳定性。同时对样品的正面和背面激光辐照对载流子的电激活效果作了比较。     

掺铒富硅氧化硅发光器件电致发光衰减机制

首先采用多靶射频磁控共溅射结合后退火工艺制备了掺Er富硅氧化硅MIS(金属-绝缘体-半导体结构)电致发光器件,然后通过电致发光(EL)以及电流-电压(I-U)特性测量对发光器件的光电性能进行表征.最后,通过对比不同富硅含量的发光器件的载流子输运机制,并通过分析器件中的电荷俘获过程,对富硅氧化硅器件中铒离子电致发光的激发和猝灭机制进行了解释.结果表明:富硅的存在改变了MIS发光器件中的载流子输运过程,造成外加电场下注入的电子能量降低,进而降低Er离子发光中心的激发效率;而富硅引入的缺陷态会引起电荷俘获及俄歇效应,也会使得发光中心发生非辐射复合过程.     

退火工艺对SiN膜及SiO2/SiN双层膜钝化特性的影响

针对硅太阳电池的背表面钝化,研究了在多晶硅P型衬底上SiN膜及SiO2/SiN双层膜的热稳定性及在不同温度下两种膜的退火特性.通过准稳态光电导衰减法测试其少数载流子寿命,发现SiN膜比较适合于在500℃以内的温度下进行常规炉热退火,而SiO2/SiN双层膜则比较适合在600~700℃之间的温度下进行常规炉热退火.对SiN膜进行链式炉热退火实验表明,低温(700~850℃)条件下表面钝化效果最好.     

多孔硅的电致发光操作模型研究

通过实验分别实现了固、液两种类型的多孔硅电致发光模型.根据液态下的化学反应,分析了"空穴消耗,电子注入"机制,解释了液态下电致发光的载流子产生和复合机制.利用固态模型的I-V特性曲线,分析了多孔硅发光二极管的载流子产生机制和发光机理.实验分析为进一步提高多孔硅电致发光效率,实现硅基光电集成打下基础.     

硅中离子注入层的卤钨灯辐照快速退火研究

本文研究了硅中离子注入层的卤钨灯辐照快速退火,对注B 和注P 样品分别测量了经1100℃、15秒和1050℃、12秒退火后注入层的载流子浓度分布,并与950℃、30分钟常规热退火样品作了比较;结果表明,卤钨灯辐照快速退火具有电激活率高、注入杂质再分布小及易于推广使用等优点.对于100keV、1×10~(15)cm~(-2)P 注入样品,经1050、10秒卤钨灯辐照退火后,表面薄层电阻为74.8Ω/□;对通过920(?)SiO_2膜,25keV、1×10~(15)cm~(-2)B 注入样品,经1100℃、15秒卤钨灯辐照快速退火后表面薄层电阻为238.0Ω/□;而经过950℃、30分钟常规热退火后,以上两种样品的表面薄层电阻分别为72.0Ω/□和245.8Ω/□.采用这种退火方法制作出了结深为0.10μm 的近突变P~ N 结,并测量了结深与退火时间的关系.     

氧化层对水分解阳极多孔Si性能的影响

通过改变腐蚀时间,研究了多孔硅的反射率、禁带宽度、发光性能,比较了退火前后多孔硅作为水分解阳极的工作性能.测试表明,当腐蚀时间为45min时,得到的多孔硅孔隙均匀,反射率低.大气退火在多孔硅表面形成了一层SiO_2,在水分解中起到很好的保护作用.对于退火样品,腐蚀时间为45min样品,电流密度较早达到稳定,腐蚀速率最小.     

多晶黑硅的制备及其组织性能

利用等离子体浸没离子注入技术在多晶硅基底上制备了黑硅材料,利用扫描电镜、分光光度计和微波光电导衰减测试仪对黑硅的组织结构、光吸收率和少数载流子寿命进行了测试分析,发现黑硅呈现多孔组织,在可见光波段的平均吸收率大于94%,其平均少数载流子寿命为5.68μs.研究了注入工艺参数对黑硅的影响,发现工作气体SF₆和O₂流量比对黑硅的组织性能影响最大,当其为2.80时制备的黑硅组织性能最好.     

Si^＋和S^＋注入SI—GaAs白光快速退火特性

研究了 Si~+和 S~+注入 SI-GaAs 经白光瞬态退火后的电特性,得出最佳的退火条件为930～960℃,5s.在适当的注入和退火条件下,得到了陡峭的载流子剖面分布没有拖长的尾巴.发现Si~+注入白光快速退火样品比常规热退火样品有较好的电特性.使用 Si~+注入白光快速退火制作出了性能良好的全离子注入平面型 MESFET.     

本征晶格缺陷对BNT铁电薄膜光响应性能的影响

用溶胶-凝胶法在YSZ/Si衬底上制备Bi3.15Nd0.85Ti3O12(BNT)铁电薄膜,研究了退火气氛和退火温度对BNT薄膜的光响应性能的影响。对不同退火气氛和退火温度下的BNT薄膜进行微观结构和光响应性能表征。研究结果表明:随着退火气氛中氧含量的降低,光响应增大,BNT薄膜中氧空位起到了为光生载流子传输提供通道的作用;随着退火温度的降低,光开启电压和饱和光电导增大,BNT薄膜中高密度的晶界虽然阻碍了光生载流子的迁移,却有利于使光生载流子在晶界处及时分开。     

本征晶格缺陷对BNT铁电薄膜光响应性能的影响简

用溶胶-凝胶法在YSZ/Si衬底上制备Bi3．15 Nd0．85 Ti3 O12（BNT）铁电薄膜,研究了退火气氛和退火温度对BNT薄膜的光响应性能的影响。对不同退火气氛和退火温度下的BNT薄膜进行微观结构和光响应性能表征。研究结果表明：随着退火气氛中氧含量的降低,光响应增大,BNT薄膜中氧空位起到了为光生载流子传输提供通道的作用;随着退火温度的降低,光开启电压和饱和光电导增大,BNT薄膜中高密度的晶界虽然阻碍了光生载流子的迁移,却有利于使光生载流子在晶界处及时分开。     

Activation of Escherichia coli prohaemolysin to the mature toxin by acyl carrier protein-dependent fatty acylation

Haemolysin secreted by pathogenic Escherichia coli binds to mammalian cell membranes, disrupting cellular activities and lysing cells by pore-formation. It is synthesized as nontoxic prohaemolysin (proHlyA), which is activated intracellularly by a mechanism dependent on the cosynthesized HlyC. Haemolysin is one of a family of membrane-targeted toxins, including the leukotoxins of Pasteurella and Actinobacillus and the bifunctional adenylate cyclase haemolysin of Bordetella pertussis, which require this protoxin activation 1-5. HlyC alone cannot activate proHlyA, but requires a cytosolic activating factor6. Here we report the cytosolic activating factor is identical to the acyl carrier protein and that activation to mature toxin is achieved by the transfer of a fatty acyl group from acyl carrier protein to proHlyA. Only acyl carrier protein, not acyl-CoA, can promote HlyC-directed proHlyA acylation, but a range of acyl groups are effective.     

As_(Hg)与V_(Hg)在碲镉汞中掺杂行为第一性原理研究

采用基于密度泛函理论的第一性原理方法,对碲镉汞材料中两种点缺陷Hg空位(VHg),As代Hg位(AsHg)及其复合缺陷(AsHg-VHg,AsHg-2VHg)进行了系统的研究,获得缺陷形成能随费米能级的变化,结合结构与电子特性分析讨论了这些缺陷在As掺杂HgCdTe中的自补偿效应和p型激活途径.     

糠醛法生产四氢呋喃中催化剂制备

催化剂Pd/C的组成设计和制备方法是糠醛液相制四氢呋喃的重要因素。分析金属Pd的催化活化机理 ,确定以浸渍法制备负载型Pd催化剂。改变制备条件可以控制催化剂的结构型式 ,提高其活性和选择性     

抗癌酶制剂L—天冬酰胺酶在甲壳素上的固定化

研究了以甲壳素为载体固定化Ｌ－天冬酰胺酶的最适条件,探讨了固定化Ｌ－天冬酰胺酶的一系列理化性质。交联剂用量、缓冲液ｐＨ值和载体活化时间均对Ｌ－天冬酰胺酶的固定化有一定影响,得到的固定化Ｌ－天冬酰胺酶的活力回收可达２５．４％。固定化Ｌ－天冬酰胺酶理化性质的实验研究表明,酶经固定化后,对蛋白水解酶的稳定性及存贮稳定性均较游离酶有很大程度的提高。     

存在集中分布界面态的异质结的C—V特性研究

提出用高频Ｃ－Ｖ法测量半导体异质结中集中分布的界面态的能位位置的方法，并分析了测试温度以及由异质结的能带偏移所引起的载流子积累对测试结果的影响，有这一方法对ＧａＳ／ＧａＡｓ和ＺｎＳｅ／ＧａＡｓ两种异质结进行了测试，发现在这两种异质界面上均存在集中分布的界面态，其能级位置分别为Ｅｃ－０．４１ｅＶ，Ｅｃ－０．５１ｅＶ。     

ZnCdSe单量子阱中点缺陷附近由非辐射载子复合激活的点缺陷反应

本文对ＺｎＣｄＳｅ单量子阱中点缺陷附近由非辐射载子复合而激活的点缺陷反应作了研究．样品在不同温度下对荧光光谱随时间变化的测量表明，这种反应增强了辐射量子效率．实验结果与温度相关的点缺陷状态跃迁率模型相吻合，并得到该跃迁的激活能为０．４５ｅｖ．     

Cyclic GMP-sensitive conductance of retinal rods consists of aqueous pores

The surface membrane of retinal rod and cone outer segments contains a cation-selective conductance which is activated by 3',5'-cyclic guanosine monophosphate (cGMP). Reduction of this conductance by a light-induced decrease in the cytoplasmic concentration of cGMP appears to generate the electrical response to light, but little is known about the molecular nature of the conductance. The estimated unitary conductance is so small that ion transport might occur via either a carrier or a pore mechanism. Here we report recordings of cGMP-activated single-channel currents from excised rod outer segment patches bathed in solutions low in divalent cations. Two elementary conductances, of approximately 24 and 8 pS, were observed. These conductances are too large to be accounted for by carrier transport, indicating that the cGMP-activated conductance consists of aqueous pores. The dependence of the channel activation on the concentration of cGMP suggests that opening of the pore is triggered by cooperative binding of at least three cGMP molecules.     

Synthesis of TiO2 supported on activated carbon by MOCVD： operation parameters study

The metallo-organic chemical vapor deposition (MOCVD) technique has been applied to the preparation of the photocatalyst titanium dioxide supported on activated carbon. The effects of various condition parameters such as carrier gas flow rate, source temperature and deposition temperature on the deposition rate were investigated. The maximum deposition rate of 8.2 mg/(g x h) was obtained under conditions of carrier gas flow rate of 400 ml/min, source temperature of 423 K and deposition temperature of 913 K. The deposition rate followed Arrhenius behavior at temperature of 753 K to 913 K, corresponding to activation energy E(a) of 51.09 kJ/mol. TiO(2) existed only in anatase phase when the deposition temperature was 773 K to 973 K. With increase of deposition temperature from 1073 K to 1273 K, the rutile content sharply increased from 7% to 70%. It was found that a deposition temperature of 773 K and a higher source temperature of 448 K resulted in finely dispersed TiO(2) particles, which were mainly in the range of 10-20 nm.     

分子导体M（dmit）_2（M＝Ni，Pd，Pt，Cu）的电导研究

测定了一组化学式为Ｍ（ｄｍｉｔ）２（Ｍ＝Ｎｉ，Ｐｄ，Ｃｕ，Ｐｔ）的分子导体的从室温至液氮温度的电导曲线，Ｐｄ（ｄｍｉｔ）２与Ｃｕ（ｄｍｉｔ）２在所测温区具有半导体的导电性；而Ｎｉ（ｄｍｉｔ）２与Ｐｔ（ｄｍｉｔ）２则有一个半导体→导体的转变．用紧束缚方法计算了Ｎｉ（ｄｍｉｔ）２的能带，在此基础上推导出与经典球型等能面模型的结果不同的载流子密度表达式，理论的导电激活能与实测值取得了较好的一致．     

Preparation and characterization of cobalt-doped iron pyrite(FeS_2) thin films

Iron pyrite (FeS_2) incorporated with cobalt dopant varying from 2%to 6%atomic ratio,was synthesized by using an aqueous hydrothermal process.The thin films of Co-doped FeS_2were fabricated by a vacuum thermal evaporation of synthesized FeS_2powder.The structural,electrical and optical properties of as-deposited and sulfurized films were investigated.The X-ray diffraction results indicated that the synthesized powder and thin films showed a cubic pyrite structure.The crystallinity of FeS_2was slightly degraded by the doping of cobalt.The dependence of thin-film resistance on the temperature indicated an increase of activation energy until 3 at%cobalt doping and then decreased the resistance with the increase of cobalt concentration.Hall effect measurements showed that the Co-doped samples have n-type conduction except for the 2 at%.The carrier concentration was in the order of 10~(18)cm~(-3),whereas,the carrier mobility decreased from 6.52 cm~2/V.s to 4.3 cm~2/V.s with the increase of cobalt dopant.The photosensitivity of undoped and cobalt-doped FeS_2films was measured under AM 1.5G and NIR light.The sulfurized films showed a higher photoresponse than the asdeposited films for both visible and IR lights.