GaAs(100)表面硫钝化的新方法:CH3CSNH2/NH4OH处理

建立了一种硫钝化GaAs(100)表面的新方法,即CH₃CSNH₂/NH₄OH溶液处理,应用同步辐射光电子能谱(SRPES)和X射线光电子能谱(XPS)表征了该钝化液处理的n-GaAs(100)表面的成键,特性和电子态.结果表明,经过处理的n-GaAs(100)表面,S既与As成键也与Ga成键,形成S与GaAs的新界面,并且Ga和As的氧化物被移走,这标志着CH₃CSNH₂/NH_{4关键词：}     

GaAs表面硫化学钝化,CH3CSNH2处理新探

应用同步辐射光电子谱（SRPES）和光致荧光（PL）方法探讨不同钝化条件对GaAs表面键合状态和电子态的影响．发现无论在酸性溶液或碱性溶液条件下，经过CH₃CSNH₂处理的GaAs表面S都与Ga和As成键，形成硫化物钝化层；钝化层形成后，PL谱的强度明显增强，表明GaAs表面复合中心的减少和缺陷态密度的降低 关键词：     

P2S5/NH4OH处理GaAs(100)表面的电子能谱研究

采用俄歇电子能谱(AES)和X射线光电子能谱(XPS)研究了P₂S₅/NH₄OH钝化液处理的GaAs(100)表面的微观特性。AES测量表明,在钝化膜和GaAs衬底之间的界面处无O组分,只有P和S组分。XPS测量分析指出,经过P₂S₅/NH₄OH溶液处理后,GaAs表面处Ga₂O₃和As₂O_{3关键词：}     

Fe(NH2trz)3·(BF4)2掺杂聚芴的有机电致发光器件

对于RGB有机电致发光器件(OLEDs),蓝光非常重要.在现有各种蓝光材料中,聚芴(PFO)非常稳定且荧光量子效率可达80%,但它有一个非常大的缺点:电致发光会产生异常绿光带.这严重影响了PFO相关器件的饱和色纯度.本文使用分子基磁性材料Fe(NH₂trz)₃·(BF₄)₂掺杂PFO方法,解决了这一难题.以ITO为衬底,制作了结构为ITO/PEDOT:PSS/PFO:Fe(NH₂trz)₃·(BF₄)₂/CsCl/Al的器件.报道了利用Fe(NH₂trz)₃·(BF₄)₂特殊的电子自旋态调制PFO的光电特性,实现了PFO的强烈纯正蓝光发射.详细研究了Fe(NH₂trz)₃·(BF₄)₂对PFO光电特性的影响.在4 V至9 V电压的偏置下,没有Fe(NH₂trz)₃·(BF₄)₂的器件,发出特别异常的绿光.然而,与此形成明显对照的是:Fe(NH₂trz)₃·(BF₄)₂掺杂的器件发出强烈的本征蓝光;PFO绿色发光带被成功压制;随着电压的变化,器件光谱的蓝光部分在整个EL谱所占比例没有改变.运用光电磁一体化测量技术,进一步研究了PFO掺杂Fe(NH₂trz)₃·(BF₄)₂器件的磁发光(MEL)和磁电导(MC)效应.发现PFO:Fe(NH₂trz)₃·(BF₄)₂和纯PFO薄膜内都没有激基缔合物产生.运用发光动力学理论,分析了Fe(NH₂trz)₃·(BF₄)₂阻断PFO异常绿光发射的机理.     

正十八硫醇钝化GaAs(100)表面特性研究

为了有效降低GaAs半导体表面态密度,提出了采用正十八硫醇（ODT,CH₃[CH₂]₁₇SH）进行GaAs表面钝化的方案。首先,分别对GaAs（100）晶片进行了常规硫代乙酰胺（TAM,CH₃CSNH₂）钝化和正十八硫醇钝化,通过X射线光电子能谱（XPS）对比分析了钝化前后晶片表面的化学成分,然后利用光致发光光谱（PL）对正十八硫醇处理的GaAs（100）晶片进行了钝化时间的优化,最后通过扫描电子显微镜（SEM）测试了钝化前后的晶片表面形貌。实验结果表明：采用正十八硫醇钝化的GaAs（100）表面,相比常规硫代乙酰胺钝化方案,具有更低的氧化物含量和更厚的硫化层厚度;室温钝化条件下,钝化时间越长,正十八硫醇的钝化效果越好,但PL强度在钝化超过24 h后基本达到稳定,最高PL强度提高了116%;正十八硫醇钝化的GaAs（100）晶片具有良好的表面形貌,表面形成了均匀、平整的硫化物钝化层。数据表明正十八硫醇是钝化GaAs（100）表面一种非常有效的技术手段。     

LaNi5的硫化物中毒及其再生的表面研究

本文概括了氢气中的硫化物(如H₂S,SO₂和CS₂)对LaNi₅的表面中毒和再生。AES,XPS的分析表明,三种硫化物的中毒性质不同:H₂S中毒产生La₂S₃和NiS这样的表面化合物;SO₂和CS₂中毒分别发生化学吸附和物理吸附。此外,从Ni(2P_3/2)谱峰强度变化,表明了在LaNi关键词：     

(NH4)2SO4，NH4NO3和(NH4)2SO4/NH4NO3混合气溶胶吸湿质量增长因子的快速测量方法

气溶胶颗粒的吸湿性决定了其尺寸、浓度、化学组成以及相态,从而显著影响着全球气候、大气异相化学以及人类健康。运用在线、原位、连续扫描衰减全反射傅里叶变换红外光谱（ATR-FTIR）技术, 结合线性湿度（RH）控制系统,实现了RH连续变化条件下气溶胶FTIR-ATR光谱的快速测量。根据水弯曲振动谱带（~1 640 cm-1）峰面积随RH的变化,得到了(NH₄)₂SO₄,NH₄NO₃和(NH₄)₂SO₄/NH₄NO₃混合气溶胶的质量增长因子（MGFs）、潮解点（DRH）和风化点（ERH）。与气溶胶的E-AIM模型预测值相比较,实验结果表现出良好的一致性,证实该方法是一种测量大气气溶胶MGFs,ERH和DRH的快速测量方法。     

氨分子在000和201带的选择光离解

本文利用脉冲紫外激光(UV)选择激发氨分子到?¹A″₂电子激发态的两个最低振动能级ν′₂=0和ν′₂=1(ν₂振动),然后检测新生态H原子的飞行谱(TOF),研究了氨分子的光碎片动力学。光谱证实了最近所测的离解能D₀⁰(H-NH₂)=4.645eV;绝大多数生成的NH₂(X²B₁)基处于非振动激发,但是具有围绕a惯性轴的高度转动激发。通过NH₃(?)的ν′₂=1光离解产生的NH₂(X)基具有较高的内部激发,并且显示了在N=K_a转动能级上的反转布居。 关键词：     

Co/S钝化GaAs(100)界面形成的SRPES研究

利用同步辐射光电发射谱研究了Co与CH\-3CSNH\-2处理的S钝化GaAs(100)的界面形成.发现 其界面反应较弱,Co覆盖层达到0.8nm时,形成稳定的界面.GaAs表面上和S原子形成桥 键的Ga原子与Co发生交换反应并扩散到覆盖层中,形成Co—S键.Co覆盖层表面无偏析As的出现,与Co/GaAs(100)界面不同,这表明GaAs表面的S钝化可有效地阻止As原子向覆盖层的扩散. 关键词：     

Tb0.3Dy0.7(Fe0.9T0.1)1.95合金的结构、自旋重取向和穆斯堡尔谱

系统研究了室温下Tb_0.3Dy_0.7(Fe_0.9T_0.1)_1.95(过渡金属元素T=Mn，Fe，Co，B，Al，Ga)合金中ⅢA族金属和过渡金属元素T替代Fe对结构、自旋重取向和穆斯堡尔谱的影响.结果发现，不同金属T替代Fe，Tb_0.3Dy_0.7(Fe_0.9T_0.1)_1.95，合金具有相同的MgCu₂型立方Laves相结构；Al，Ga替代使Tb_0.3Dy_0.7(Fe_0.9T_0.1)_1.95合金的易磁化方向在{110}面逐渐偏离了立方晶体的主对称轴，即自旋重取向，B，Mn，Co替代未使易磁化轴发生明显转动；Al，Ga元素替代使超精细场H_hf略有下降，B，Mn替代对超精细场H_hf的影响不大，而Co元素替代使超精细场H_hf有较大增加；所有元素替代使同质异能移IS有所增加；B，Al，Ga和Mn替代使四极劈裂Q_s增加，而Co替代使四极劈裂Q_s下降. 关键词： 立方Laves相 自旋重取向 穆斯堡尔谱     

Improved GaSb surfaces using a (NH4)2S/(NH4)2S04 solution

Bulk (1 0 0) n-GaSb surfaces have been treated with a sulphur based solution ((NH₄)₂S/(NH₄)₂SO₄) to which sulphur has been added, not previously reported for the passivation of GaSb surfaces. Au/n-GaSb Schottky barrier diodes (SBDs) fabricated on the treated material show significant improvement compared to that of the similar SBDs on the as-received material as evidenced by the lower ideality factor (n), higher barrier height (?_b) and lower contact resistance obtained. Additionally, the reverse leakage current, although not saturating, has been reduced by almost an order of magnitude at −0.2 V. The sample surfaces were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The native oxide, Sb–O, present on the as-received material is effectively removed on treating with ([(NH₄)₂S/(NH₄)₂SO₄]+S) and (NH₄)₂S. Analysis of the as-received surface by XPS, prior to and after argon sputtering, suggests that the native oxide layer is ≤8.5 nm.     

Improvement of Atomic-Layer-Deposited Al2O3/GaAs Interface Property by Sulfuration and NH3 Thermal Nitridation

Fermi level pinning at the interface between high-h gate dielectric and GaAs induced by unstable native oxides is a major obstacle for high performance GaAs-based metal-oxide-semiconductor （MOS） devices. We demonstrate the improved Al2O3/GaAs interracial characteristics by （NH4）2S immersion and NH3 thermal pretreatment prior to A1203 deposition. X-ray photoelectron spectroscopy （XPS） analysis confirms that sulfuration of GaAs surface by （NH4 ）2S solution can effectively reduce As-O bonds while Ga-O bonds and elemental As still exist at Al2O3 /GaAs interface. However, it is found that N incorporation during the further thermal nitridation on sulfurated GaAs can effectively suppress the native oxides and elemental As in the sequent deposition of Al2O3. Atomic force microscopy （AFM） shows that the further thermal nitridation on sulfurated GaAs surface can also improve the surface roughness.     

Optimisation of the ammonium sulphide (NH4)2S passivation process on In0.53Ga0.47As

The passivation of III-V semiconductor materials with sulphur is widely reported to reduce interface state defects and improve semiconductor device performance. The most common approach utilises ammonium sulphide ((NH₄)₂S), however there are wide variations in the reported processing parameters involved in this procedure. This study provides a comprehensive review of the various parameters used as well as determining the optimal processing conditions in terms of sample pre-treatments, temperature of the (NH₄)₂S solution, length of time the sample is in the solution and (NH₄)₂S concentration, by measuring the level of residual native oxides and surface roughness by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively.     

Esca studies of Ga,As, GaAs,Ga2O3, As2O3 and As2O5

The binding energies of Ga 3d, As 3d, Ga L₃M₄,₅M₄,₅ and O 1s in Ga, As, GaAs, Ga₂O₃, As₂O₃ and As₂O₅ are reevaluated by means of ESCA. The calibration lines of the C 1s and the Au 4f_{$\text{7}\text{2}$} gave different binding energies for the compound materials. In order to determine the absolute binding energies, the chemical shifts in Auger and photoelectron lines from a layered structure composed of thin layer oxide and substrate of a defined material were used. An energy calibration curve, E(Ga 3d) vs. ΔE(GA LMM - Ga 3d), was found to be useful for determination of binding energies in the material which contains gallium. In the case of the GaAs sample, both the chemical etching and the ion bombardment effects on the chemical structure of the GaAs surface are also discussed.     

Effect of chemical surface treatments on interfacial and electrical characteristics of atomic-layer-deposited Al2O3 films on Ge substrates

The Ge surfaces were cleaned and passivated by two kinds of chemical pretreatments: conventional combination of HF + (NH₄)₂S, and new one of HBr + (NH₄)₂S. The chemical states and stability at passivated Ge surfaces were carefully characterized. The influence of chemical surface treatments on the interface and electrical properties of Al₂O₃ gate dielectric films on Ge grown by atomic layer deposition (ALD) has been investigated deeply. It is found that the combination of HBr and (NH₄)₂S can remove more Ge-O bonds on the Ge surface compared to that of conventional HF and (NH₄)₂S with excellent stability. X-ray photoelectron spectroscopy (XPS) reveals that HBr and (NH₄)₂S treated Ge surface has a mixture states of GeO_x (9.25%) and GeS (7.40%) while HF and (NH₄)₂S treated Ge surface has a mixture states of GeO_x (16.45%) and GeS (3.37%). And the Ge-S peak from the surface of Ge substrates decreases a little after the HBr and (NH₄)₂S treated Ge surface was exposed in the ambient for 300 min, which suggests the Ge surface is stable to oxidants. The Al₂O₃ films on HBr and (NH₄)₂S treated Ge substrates exhibits better electrical properties such as large capacitance, decreased leakage current density by ∼two orders of magnitude, and less C-V hysteresis. This indicates that a reduction in charge traps possibly at the interface and more interface traps are terminated by sulfur. The surface treatment of HBr and (NH₄)₂S seems to be very promising in improving the quality of high-k gate stack on Ge substrates.     

Realization of controllable etching for ZnO film by NH4Cl aqueous solution and its influence on optical and electrical properties

ZnO films were deposited on c-plane Al₂O₃ substrates by pulsed laser deposition. The etching treatments for as-grown ZnO films were performed in NH₄Cl aqueous solution as a function of NH₄Cl concentration and etching time. It was found that NH₄Cl solution is an appropriate candidate for ZnO wet etching because of its controllable and moderate etching rate. The influence of etching treatment on the morphology, optical and electrical properties of the ZnO films has been investigated systematically by means of X-ray diffraction, atomic force microscope, photoluminescence and Hall effect. The results indicated that the surface morphology and optical properties of the films were highly influenced by etching treatment.     

PASSIVATION OF THE InP(100) SURFACE USING (NH4)2Sx

InP(100) surface treated with (NH₄)₂S_x has been investigated by using photolumines-cence(PL), Auger electron spectroscopy and X-ray photoelectron spectroscopy, It is found that PL intensity increased by a factor of 3.3 after (NH₄)₂S_x passivation and the sulfur remained on the surface only bonded to indium, not to phosphorus. This suggests that the sulfur atoms replace the phosphorus atoms on the surface and occupy the phosphorus vacancies.     

Studies of thermal decomposition of (NH4)2Fe(SO4)2·6H2O

Thermal decomposition products of the Mohr salt (NH₄)₂Fe(SO₄)₂·6H₂O have been studied and identified using the Mössbauer effect, X-ray diffraction, infrared spectroscopy, and the gravimetric and thermal differential methods. It has been found that the Mohr salt heated for 96 hr. in air at 520K changes to a single substance identified as NH₄Fe(SO₄)₂ with a single Mössbauer line (width 0.30 mm/sec; isomeric shift 0.30 mm/sec). When the Mohr salt is heated for 1 hr. in air at 770 K it changes to Fe₂(SO₄)₃ with a single Mössbauer line (width 0.33 mm/sec; isomeric shift 0.31 mm/sec) strikingly similar to line of NH₄Fe(SO₄)₂.