摘要:

We present a model of the production of deep centers and their reactions following electron irradiations in InP. We propose that the dominant hole traps inp‐InP and electron traps inp+nInP junctions are complexes between shallow acceptors and a common intrinsic entity, the phosphorus interstitial or vacancy. The reactions observed below and above room temperature are then due to a local mobility of this entity, which can be obtained as well by thermal as by electronic stimulation of the reactions. This model implies the long‐range migration (at least down to 16 K) of this entity, and explains the strongly different behavior ofn‐InP compared top‐InP samples.

ISSN:0021-8979    

DOI:10.1063/1.337453

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Electron microscopy/diffraction and electron energy‐loss spectroscopy, including low‐loss and core‐edge structures, were used to characterize and study the atomic arrangement in amorphous SnO2prepared by reactive sputtering. The gross features in the energy‐loss spectra are the same as for crystalline SnO2, whereas the fine structures are smeared out. The diffraction pattern of amorphous SnO2is qualitatively well described by assuming each tin atom to be surrounded by six oxygen atoms at a distance of 2.05 A˚, two tin atoms at 3.19 A˚, and eight tin atoms at 3.71 A˚, which suggests the same local atomic arrangement as in crystalline SnO2.

ISSN:0021-8979    

DOI:10.1063/1.337454

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Specific heat data are reported on pure and varistor ZnO, 1.7–25 K, and thermal conductivity data are reported on varistor ZnO, 1.7–15 K. In pure ZnO interstitials give rise to an Einstein contribution (&ohgr;E=84 cm−1) to the specific heat above 10 K and to a Schottky contribution (&dgr;&bartil;10−5eV) below 4 K due possibly to ordering. The calorimetric Debye temperature is 399.5 K. In varistor ZnO the specific heat is dominated below 20 K by compensating charge densities (∼1018cm−3) on the interfacial barriers which give rise to two Schottky terms (&dgr;=7×10−4and 3×10−3eV). All of these non‐Debye excitations are localized (do not carry heat). No evidence is seen in the thermal conductivity for Kapitza‐resistance effects at the heavily doped grain boundaries.

ISSN:0021-8979    

DOI:10.1063/1.337455

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Thermal expansion of the hexagonal (4H) polytype of SiC was measured from 20 to 1000 °C by the x‐ray diffraction technique. The principal axial coefficients of thermal expansion are expressed by the second‐order polynomials: &agr;11=3.21×10−6+3.56×10−9T−1.62×10−12T2, and  &agr;33=3.09×10−6+2.63×10−9T−1.08×10−12T2(°C−1). The &agr;11is larger than the &agr;33over the entire temperature range, yielding a thermal expansion anisotropy ‘‘A’’ of 0.04 at room temperature which increases to 0.11 at 1000 °C. The thermal expansion of the (4H) structure is compared with previously published results for the cubic (3C) and the hexagonal (6H) SiC polytypes.

ISSN:0021-8979    

DOI:10.1063/1.337456

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A new intrinsic gettering process was found in silicon crystals subjected to a three‐step annealing sequence. The process involves native point defects (silicon interstitials) rather than residual oxygen impurity, and thus it can be realized in crystals with low or virtually zero oxygen concentration. The key characteristics of the process (i.e., denuding and gettering efficiency and the role of annealing ambient) are discussed in conjunction with a kinetic model involving diffusion of silicon interstitials. The identity of the intrinsic gettering centers was pursued by transmission electron microscopy.

ISSN:0021-8979    

DOI:10.1063/1.337457

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Intrinsic gettering centers in oxygen‐free silicon crystals after a high–low–medium‐temperature annealing cycle were successfully identified using transmission electron microscopy and energy dispersive x‐ray spectroscopy. These centers have a butterfly‐type shape and they consist of interstitial‐type extended multiple dislocation loops in {110} planes of 0.1–0.7 &mgr;m diameter and a high density of small 3–15‐nm‐diam precipitates located inside the dislocation loops and/or on the dislocation line. Compositional x‐ray analysis identified Cu as the predominant metal component of the precipitates. Occasionally Ni and very rarely Fe were also detected.

ISSN:0021-8979    

DOI:10.1063/1.337458

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Arsenic has been implanted into TiSi2films to study its diffusivity during subsequent annealing between 600 and 800 °C in vacuum. The diffusion coefficient turns out to be so high that the As redistributes over the entire TiSi2film (thickness 200 nm) at temperatures as low as 600 °C. In addition to this some of the As segregates at the TiSi2/polycrystalline Si interface and part of the implanted As remains immobile in the as‐implanted distribution. The mobile fraction is limited by the solubility of As in TiSi2which has been determined from the As concentration in the bulk. This solubility turns out to be quite substantial and could be described by a Boltzmann relation with an activation energy of 1 eV and a preexponential factor of 1.06×1025at/cm3. Evaporation of As occurs above 600 °C and can be prevented by oxidizing the TiSi2film. The electrical resistivity and the stress of the silicide film indicate that implantation damage can only be eliminated by annealing at 800 °C, the sintering temperature of the silicide.

ISSN:0021-8979    

DOI:10.1063/1.337459

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have investigated the formation of titanium silicide by rapid thermal annealing in nitrogen and argon ambients over polycrystalline silicon. A sheet resistance of about 3 &OHgr; per square for a 300‐A˚ Ti layer was achieved after 900 °C/10‐s annealing treatment, which decreased to about 2 &OHgr; per square after 1100 °C/10‐s treatment. The silicides were found to be stable during rapid thermal annealing up to 1100 °C/10 s with no or negligible migration of titanium along the grain boundaries in polycrystalline silicon. An external layer (titanium rich, mixture of titanium oxide and nitride) was observed to form during rapid thermal annealing treatment in the nitrogen ambient, but the surface remained clean in the argon ambient.

ISSN:0021-8979    

DOI:10.1063/1.337404

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Aluminum layers of some nanometers thickness have been deposited onto &agr;‐SiC crystals and studied by x‐ray and ultraviolet photoelectron spectroscopies as a function of annealing temperature. Annealing beyond 600 °C induces a complete disappearance of metallic Al on the crystal surface, penetration of Al into the bulk, and formation of aluminum carbide. Ultraviolet photoemission spectra recorded after annealing at 360 °C could be explained by a beginning of interfacial reaction. However, there is no clear experimental evidence that reaction occurs at such a low temperature.

ISSN:0021-8979    

DOI:10.1063/1.337405

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Trap levels in ∼2‐&mgr;m In0.2Ga0.8As (94 A˚)/GaAs(25 A˚) strained‐layer superlattices, suitable for optical waveguides, have been identified and characterized by deep‐level transient spectroscopy and optical deep‐level transient spectroscopy measurements. Several dominant electron and hole traps with concentrations ∼1014cm−3, and thermal ionization energies &Dgr;ETvarying from 0.20 to 0.75 eV have been detected. Except a 0.20‐eV electron trap, which might be present in the In0.2Ga0.8As well regions, all the other traps have characteristics similar to those identified in molecular‐beam epitaxial GaAs. Of these, a 0.42‐eV hole trap is believed to originate from Cu impurities and the others are probably related to native defects. Upon Si implantation and halogen lamp annealing, new deep centers are created. These are electron traps with &Dgr;ET=0.81 eV and hole traps with &Dgr;ET=0.46 eV. Traps occurring at room temperature may present limitations for optical devices.

ISSN:0021-8979    

DOI:10.1063/1.337406

出版商:AIP    

年代:1986

数据来源: AIP