摘要:

X‐ray photoemission spectroscopy was used to analyze the oxide grown at low temperature on AuxSi1−xfilms. It was found that the oxide is stoichiometric SiO2, but is structurally distinct from oxides grown on Si at high temperatures (950 °C). Also, unoxidized Au‐Si atom inclusions were observed in the oxide. The composition of the inclusions is dependent on the initial bulk AuxSi1−xcomposition.

ISSN:0021-8979    

DOI:10.1063/1.345610

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Aluminum alloys have virtually replaced aluminum thin films for interconnections in very large‐scale integration because of their improved reliability. Mechanical stress is a problem of growing importance in these interconnections. Stress as a function of temperature was measured for thin aluminum films on an oxidized silicon substrate and several aluminum alloys and layered films consisting of silicon, copper, titanium, tungsten, tantalum, vanadium, and TiSi2. Solid‐state reactions of the aluminum with the additives and with the ambient during thermal cycling will occur, and depending on what compounds have formed and at what temperature, this will determine the morphology and reliability of the metallization. The measurement technique, based on determination of wafer curvature with a laser scanning device, directly measures the total film stress and reflectivityinsituas a function of temperature during thermal cycling. Changes in stress were detected when film composition and structure varied and were correlated using x‐ray diffraction with the formation of aluminides. Other phenomena that contribute to stress changes include elastic behavior, recrystallization, grain growth, plastic behavior, yield strength, and film hardening from precipitates.

ISSN:0021-8979    

DOI:10.1063/1.345611

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Ultrathin films of F‐bridged Al‐phthalocyanine polymer, (AlPcF)n, grown by the molecular‐beam epitaxy technique show unusual spectroscopic properties which can be described by the possibility of pseudomorphic layer formation at the thin‐film/substrate interface. A change in the electronic structure of the molecules of this layer is presumed to occur. The existence of the layer is directly related to the degree of epitaxy.

ISSN:0021-8979    

DOI:10.1063/1.345612

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The critical thickness‐strain relationships for buried strained layers and strained‐layer superlattices (SLSs) are derived using an energy balance model. Relaxation of the entire heterostructure and individual strained layers by both 60° typea/2⟨011⟩ and pure edge dislocations is considered. GexSi1−x/Si heterostructures designed to investigate the stability regimes predicted by the model were grown by molecular‐beam epitaxy. The extent of relaxation and the detailed dislocation structure were assessed in annealed structures by x‐ray rocking curve analysis, transmission electron microscopy, and Nomarski microscopy of etched samples. Comparison of metastable as‐grown and post‐growth annealed microstructures revealed the evolution of misfit dislocation structure as equilibrium was approached on annealing in the temperature range 600–900 °C. The predominant relaxation mechanism for most GexSi1−x/Si heterostructures was by 60°a/2 ⟨011⟩ misfit dislocations at the first strained‐layer/substrate interface. However, for SLSs with strained layers exceeding their individual critical thickness, pairs of dislocations and prismatic loops on (011) planes were observed entrained within the GexSi1−xlayers. The agreement between experimentally observed relaxation behavior and the critical thickness versus strain predictions of the energy balance model is remarkable. Superlattices and buried strained layers were found to be only slightly more stable than an uncapped strained layer of the equivalent strained‐layer thickness. Interdiffusion was observed at annealing temperatures above 800 °C; annealing at 900 °C for 30 min was sufficient to eliminate the strain and composition modulation in a superlattice with a 55‐nm period andx=0.25. The relative influence of the various strain relaxation mechanisms is discussed for the alloy range 0<x<1 and for geometries with strained‐layer dimensions varying from 0.8 to ∼500 nm.

ISSN:0021-8979    

DOI:10.1063/1.345613

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Previously it has been shown that the electronic surface properties of GaAs can be improved by photochemical treatment in water. If this photowashing technique is carried out with intense white light, oxides several hundred angstroms thick can be grown. This paper reports the structure and composition of this photowashed oxide and one grown by soaking in stagnant water in low light. The oxide was determined by TEM cross sections to be highly porous, but with thin continuous oxide layers both at the surface and at the oxide/GaAs interface. The oxide is composed of Ga2O3with a low concentration of As2O3. The layer is primarily a fine grain Ga oxide crystal with a structure which appears different from the common forms of Ga2O3.

ISSN:0021-8979    

DOI:10.1063/1.345614

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The interaction of amorphous MoNixalloys with silicon has been investigated by glancing‐angle x‐ray diffraction, Auger‐electron spectroscopy, and sheet‐resistance measurements in the temperature range 500–700 °C. Mo‐rich alloys (Mo80Ni20and Mo65Ni35) were found to react with silicon at ∼550 °C while nickel‐rich alloys (Mo32Ni68) react at ∼500 °C to form silicides. In Mo‐rich alloys, the initial reaction occurs due to out‐diffusion of nickel from the alloy and in‐diffusion of silicon into the alloy, while in nickel‐rich alloys the initial reaction occurs due to out‐diffusion of nickel only. In the initial phase of the reaction, a mixture of several crystalline phases of molybdenum and molybdenum and nickel silicides is observed. At higher temperature, however, a two‐layer structure MoSi2+NiSi(NiSi2)/ NiSi(NiSi2)/ Si(100) is formed in both cases.

ISSN:0021-8979    

DOI:10.1063/1.345615

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Raman spectroscopy is used to investigate the structural changes in isochronally annealeda‐Ge/SiOxsuperlattices. The Ge crystallization temperature is found to be higher in superlattices with thinner Ge layers, which can be interpreted in terms of the retardation of nucleation and growth of Ge microcrystallites near the Ge/SiOxinterface. Before and after the Ge layers crystallize there is Si diffusion into the Ge layers. The Si appears to be uniformly distributed throughout the Ge layers.

ISSN:0021-8979    

DOI:10.1063/1.345616

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Deep level transient spectroscopy and transport properties measurements were performed on close‐spaced vapor transport deposited epitaxial GaAs. The deep EL2 donor level was consistently observed in all of the layers. A side band at around 300 K was found to be present in relatively high concentration close to the as‐grown surface of the epitaxial films. The multilevel impurity model treatments suggest the existence of an off‐stoichiometry‐induced deep acceptor level, related to possible gallium vacancies, in As‐rich GaAs.

ISSN:0021-8979    

DOI:10.1063/1.345617

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The photocapacitance (PHCAP) method in the constant capacitance condition has been applied to determine the energy and density of deep levels within the limits of a certain depletion layer thickness as a function of the photon energy and the applied voltage. Samples used were variousn‐type GaAs crystals annealed for a long time under excess As vapor pressure and rapidly cooled. The present PHCAP investigations have revealed several stoichiometry‐dependent deep levels including some photoquenching levels. These areEc−0.66 and −0.72 eV deep donors, the photoquenching level at 1.03, 1.25, and 1.41 eV. The As‐vapor‐pressure dependence of the density of these deep levels in quasithermal equilibrium were also clarified. The 1.25‐eV photoquenching level density increased monotonically with increasing applied As vapor pressure and finally saturated at extremely high As vapor pressures. The density ofEc−0.72 eV deep donors showed a similar dependence on the As vapor pressure, but showed less saturation under higher As vapor pressures. TheEc−0.72 eV deep donor is quite different from the so‐called EL2 level. But the temperature dependence of the PHCAP responses (&Dgr;Vph‐T) revealed strong interaction effects among these defect structures. From the photoluminescence results and conventional deep‐level transient spectroscopy measurements,it was clarified that bothEc−0.66 and −0.72 eV deep donors had larger Frank–Condon shifts, 0.28 and 0.24 eV, respectively, compared with that of the so‐called EL2 level (0.12 eV). The PHCAP measurements after photoexcitation were carried out to detect de‐ionization of the photoionized deep levels. Additional de‐ionization of the photoionized state of the 1.41‐eV photoquenching level was detected adjacent to those of the EL2 level. These de‐ionization could be detected only in the course of the photoquenching phenomenon inn‐type GaAs. The As‐vapor‐pressure dependence of these deep levels shows that interstitial As atoms play a vital role in forming deep levels in annealed GaAs crystals.

ISSN:0021-8979    

DOI:10.1063/1.345618

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Hydrogen passivation of chalcogen impurities (S, Se, and Te) inn‐ andp‐type silicon was studied by deep‐level transient spectroscopy (DLTS). After exposure to monatomic hydrogen from a remote microwave plasma, the chalcogen‐related double‐donor defects were completely neutralized near the exposed surface of the silicon samples (at 150 °C). Vacuum anneals of hydrogenated specimens revealed that the two donor levels of each chalcogen complex recover simultaneously. Reactivation of the double donors was quantitatively examined with DLTS measurements of hydrogenated specimens after isothermal anneals. The activation energies for reactivation of the neutralized chalcogen‐impurity complexes are as follows: For isolated substitutional sulfur, selenium, and tellurium, the energies are 1.61±0.21 eV, 1.39±0.17 eV, 1.39±0.18 eV, respectively, and for the pure pairs of sulfur and selenium, they are 1.56±0.2 eV and 1.41±0.18 eV, respectively. The experimental results are discussed with regard to available calculations for hydrogen passivation of the sulfur impurity in silicon.

ISSN:0021-8979    

DOI:10.1063/1.346096

出版商:AIP    

年代:1990

数据来源: AIP