GaAs光电阴极原位光谱响应测试技术研究

阐述了ＧａＡｓ光电阴极的原位光谱响应曲线的测试原理,介绍了ＧａＡｓ光电阴极激活和评估系统,该系统可在ＧａＡｓ光电阴极激活过程中在线测试其在４００～１２００ｎｍ之间的光谱响应曲线,给出并分析了该系统对反射式ＧａＡｓ光电阴极的测试结果。结果表明,利用国产材料激活的ＧａＡｓ光电阴极已为负电子亲和势阴极。     

复合型Si光电发射材料

采用碱锑化合物的镀制与铯氧激活可制备复合型Ｓｉ光电发射材料（Ｓｉ－Ｎａ＿２Ｓｂ－Ｃｓ）－Ｏ－Ｃｓ，（Ｓｉ－Ｋ＿３Ｓｂ－Ｃｓ）－Ｏ－Ｃｓ，（Ｓｉ－Ｃｓ＿３Ｓｂ－·Ｃｓ）－Ｏ－Ｃｓ和（Ｓｉ－Ｎａ＿２ＫＳｂ－Ｃｓ）－Ｏ－Ｃｓ，其最高灵敏度分别可达９５０，１０５０，１５０和２０００μＡ／１ｍ，其最低逸出功分别已达１．０，０．９，０．８５和０．９ｅＶ。比较了复合型Ｓｉ光电发射材料与Ｓｉ和Ｎａ＿２ＫＳｂ（Ｃｓ）光电材料的一些性能参数，提出了复合型Ｓｉ光电材料的表面原子模型；讨论了复合型Ｓ光电材料的光电发射过程并分析了碱锑过渡层的作用。     

光阴极材料GaAs／AlGaAs的组分分析

为探索砷化我阴极的光电灵敏度的影响因素,利用Ｘ射线光电子能谱、二次离子擀谱和电化学方法测试和分析了国内和国外ＧａＡｓ光阴极材料ＧａＡｓ／ＡｌＧａＡｓ的Ｃ,Ｏ含量的空穴深度分布。实验发现,国内的材料在ＧａＡｓ／ＡｌＧａＡｓ 面及ＡｌＧａＡｓ层的Ｏ含量分别为７．６％和１０．６％,Ｃ深度分别为５．２×１０＾１８ａｔｏｍｓ／ｃｍ＾３和１．０×１０＾１９ａｔｏｍｓ／ｃｍ＾３,而国外的材料的Ｏ含量相应为１．０     

InGaAs/InP中离子注入和新型HPT

ＩｎＧａＡｓ／ＩｎＰ是制作光电器件与微波器件的重要材料。离子注入ＩｎＧａＡｓ／ＩｎＰ做掺杂或制作高阻层是人们十分关注的研究课题。采用Ｆｅ＾＋注入ＩｎＧａＡｓ／ＩｎＰ得到了电阻率升高的好结果。用Ｂｅ＾＋注入制作了新结构ＨＰＴ的基区。研制成功了在１．５５μｍ波长工作的ＩｎＧａＡｓ／ＩｎＰ新结构光电晶体管,在０．３μＷ入射光条件下,光电增益为３５０。     

InAlAs／InGaAs MSM光电探测器

采用ＧＳＭＢＥ方法及典型的器件工艺制成了用ＩｎＡｌＡｓ作为肖特基势垒增强材料的高性能ＩｎＡｌＡｓ／ＩｎＧａＡｓ／ＩｎＰ ＭＳＭ光电探测器。用自制的测试系统对器件的直流和瞬态特性进行了测试，测试结果表明，器件的击穿电压大于３０Ｖ，在１０Ｖ偏压下暗电流小于２０ｎＡ，对应的暗电流密度为３ｐａ／μｍ＾２，优于已有文献的报导。     

Ge/GaAs中APD及薄膜性能研究

研究了一种光纤通讯用光电探测器。在ＧａＡｓ上蒸镀８００ｎｍ的Ｇｅ,并在此材料基础上提出了一种吸收倍增分离的雪崩二极管（ＳＡＭ－ＡＰＤ）的结构设计,采用ＧａＡｓ作为倍增区,Ｇｅ作为吸收区。在此结构上初步制作的二极管正向开启电压为０．２￣０．３Ｖ,反向击穿电压为２．５Ｖ,漏电不明显,ｐ－ｎ结特性良好。     

δ－掺杂GaAs／AlxGa_（1－x）As二维电子气结构材料的GSMBE生长与特性

本文用ＧＳＭＢＥ技术生长纯度ＧａＡｓ和δ－掺杂ＧａＡｓ／Ａｌ_ｘＧａ_（１－ｘ）Ａｓ结构二维电子气材料并对其电学性能进行了研究。对于纯度ＧａＡｓ的ＧＳＭＢＥ生长和研究，在低掺Ｓｉ时，载流子浓度为２×１０~（１４）ｃｍ~（－３），７７Ｋ时的迁移率可达８４，０００ｃｍ~２／Ｖ．ｓ。对于用ＧＳＭＢＥ技术生长的δ－掺杂ＧａＡｓ／Ａｌ_ｘＧａ_（１－ｘ）Ａｓ二维电子气材料，在优化了材料结构和生长工艺后，得到了液氮温度和６Ｋ迁移率分别为１７３，５８３ｃｍ~２／Ｖ．５和７．６７×１０~５ｃｍ~２／Ｖ．ｓ的高质量ＧａＡｓ／Ａｌ_ｘＧａ_（１－ｘ）Ａｓ二维电子气材料。     

C70在GaAs电极上的光电性能研究

在光电化学电池中测定Ｃ７０球稀在ＧａＡｓ电极上所形成异质结的光伏效应，并研究不同介质电对和Ｃ７０薄膜厚度对光伏效应的影响，结果表明，１）Ｉ２／Ｉ３是较佳的介质电对，２）Ｃ７０薄膜厚度约为１μｍ时光伏效应较大，３）Ｃ７０在ＧａＡｓ电极上的光电性能是优良的。     

GaInAsSb共振腔增强光电探测器设计

本文用一插值和介电常数的计算模型,得到了ＧａＩｎＡｓＳｂ四元系２．４μｍ探测器材料的 份及其折射率。将传统的Ｐ－ｉ－ｎ－ＧａＩｎＡｓＳｂ探测器结构置于两组ＡｌＡｓＳｂ／ＧａＳＢ Ｂｒａｇｇ反射镜之间,可以得到接近１的量子效率。本文用传递矩阵方法（ＴＭＭ）计算了ＡｌＡｓＳｂ／ＧａＳｂ Ｂｒａｇｇ反射镜的反射率与波长及反射镜个数的关系,并对探测器的结构进行了设计,讨论了吸收系数与波长的函数对探测器量子     

电子束蒸镀半导体光电器件的增透膜

用自动电子束蒸发设备，蒸镀用于光纤通信等中的ＧａＡｓ和ＩｎＰ系列双异质结红外发光二极管的增透膜。结果表明，对波长为０．８μｍ左右的ＧａＡｌＡｓ／ＧａＡｓ发光二极管，蒸镀四分之一波长厚的Ａｌ２Ｏ３介质膜后，其输出光功率在５０ｍＡ和１００ｍＡ电流注入，可增加２５－３５％，最大可增加－５０％。对１．３μｍ波长的ＩｎＰ系列红餐发光管，用ＺｒＯ２作介质增透膜效果更好。     

Deposition and assessment of thin dielectric films on photocathode substrate made of Kodial glass

The development of Cs₃Sb transmissive interference cathode technology needs processing of such photocathodes on thin dielectric films coated on glass substrates. Here the use of such films as light resonators is made for reducing the light losses due to reflection at the cathode surface. Consequently the sensitivity of the photocathode is enhanced. TiO₂ and SiO films are chosen for their good optical properties with Cs₃Sb photocathodes in interference photoemission. Deposition methods and instrumentation in assessing their properties are discussed.     

银氧铯光电阴极的多光子光电产额

银氧铯光电阴极至今仍为一种重要的实用光电阴极,本文以银氧铯光电阴极为例,利用吴全德提出的有关模型和量子力学微扰论的结果,讨论了它的光强依赖关系,并导出了必要的公式;既为对实验结果的一种预测,也与现有实验结果符合很好。     

Te concentration dependent photoemission and inverse-photoemission study of FeSe1−xTex

Abstract

We have characterized the electronic structure of FeSe_1?xTe_x for various x values using soft x-ray photoemission spectroscopy (SXPES), high-resolution photoemission spectroscopy (HRPES) and inverse photoemission spectroscopy (IPES). The SXPES valence band spectral shape shows that the 2 eV feature in FeSe, which was ascribed to the lower Hubbard band in previous theoretical studies, becomes less prominent with increasing x. HRPES exhibits systematic x dependence of the structure near the Fermi level (E_F): its splitting near E_F and filling of the pseudogap in FeSe. IPES shows two features, near E_F and approximately 6 eV above E_F; the former may be related to the Fe 3d states hybridized with chalcogenide p states, while the latter may consist of plane-wave-like and Se d components. In the incident electron energy dependence of IPES, the density of states near E_F for FeSe and FeTe has the Fano lineshape characteristic of resonant behavior. These compounds exhibit different resonance profiles, which may reflect the differences in their electronic structures. By combining the PES and IPES data the on-site Coulomb energy was estimated at 3.5 eV for FeSe.     

Investigation of adenine, uracil, and ribose phosphate thin films prepared by electrospray in vacuum deposition using photoemission spectroscopy

Previous results showed significant ionization energy differences between thin films of the four ribonucleic acid (RNA) polynucleotides. The experiments reported here aim at the investigation of the origin of these differences. Since the ribose phosphate backbone is common to all RNA nucleotides, the nucleobases are the most likely candidate defining the ionization energy of RNA. Consequently, experiments were performed to investigate the electronic structure and ionization energies of thin films of two nucleobases (adenine and uracil, representative for purines and pyrimidines), and ribose phosphate. These experiments were performed using x-ray and ultraviolet photoemission spectroscopy (XPS, UPS) in conjunction with an electrospray based in vacuum multi-step deposition technique. The presented results clearly demonstrate a significant ionization energy difference between the two nucleobases, qualitatively matching the previous results on the homopolymers of adenosine and uridine (poly rA, poly rU). As expected, the ionization energy of the prepared ribose phosphate thin films was much larger than those of the nucleobases.     

有机半导体二萘嵌苯在Ru(0001)表面上有序结构的电子态

在Ru(0001)表面上,四个与有机半导体二萘嵌苯(Perylene)分子轨道相关的谱峰分别位于费米能级以下4.5、6.3、7.2、9.9 eV处.在界面处它们的结合能相对较低,反映了界面处有机吸附层与衬底之间的相互作用,衬底中的电子部分地转移到了有机分子的一个或几个轨道上了.低能电子衍射的结果表明:当沉积厚度接近一个单层时,Perylene分子在Ru(0001)表面上形成一种类似(4×4)的有序结构.角分辨紫外光电子能谱的结果表明:Perylene分子平面平行于Ru(0001)表面,而分子的长轴沿[1000]方向取向.随着衬底温度的上升,有机半导体材料在Ru(0001)表面以脱附的形式逐渐减少,在150 ℃以下没有分解发生.     

Au与p-CZT接触的界面势垒研究

用同步光电子能谱研究了NH4F/H2O2钝化p-CZT表面效应, 钝化处理晶体表面后,表面态能峰消失.用未钝化和钝化两种工艺方法来对比p-CZT晶体表面的钝化效果.同时用同步光电子能谱研究了Au与p-CZT接触的界面势垒.其中界面势垒可以由价带区域的新能级EV-C 和新能级与Fermi能级的差决定.未钝化和钝化的Au/p-CZT的界面势垒分别为(0.88±0.1)eV和(1.17±0.1)eV.     

A photoemission study of the ceria and Au-doped ceria/Cu(111) interfaces

The photoelectron spectroscopy (PES) study compares electronic states in three different ceria thin film surfaces prepared on a Cu(111) single-crystal surface by vapour deposition under different conditions: at 250 °C, at room temperature and finally Au-doped ceria film obtained by simultaneous deposition of Au and CeO₂ at room temperature (RT). Electronic properties of the layers and interaction of gold with CeO₂ were investigated using synchrotron-radiation-excited PES and resonant photoemission (Ce 4d → 4f transitions). We observed partial Ce⁴⁺ → Ce³⁺ reduction induced by the decrease of deposition temperature to RT instead of 250 °C and also by doping ceria with gold, accompanied by a 4f resonance enhancement of the Ce³⁺ species. In the case of the Au-doped sample the surface reduction degree is stronger and can be explained by the possible creation of a new ionic Au⁺ state observed in the Au 4f spectra.