摘要:

The dielectric constants (&kgr;’) and dielectric loss values of 10 rare‐earth gallium garnets and 1 rare‐earth aluminum garnet were measured at 1 MHz using a two‐terminal method with empirically determined edge corrections. The results are: &kgr;’(Dy3Al5O12)=11.07±0.05; &kgr;’(Ho3Ga5O12) =12.38±0.05; &kgr;’(Dy3Ga5O12)=12.36±0.06; &kgr;’(Tb3Ga5O12) =12.40 ±0.03; &kgr;’(Gd3Ga5O12) =12.18±0.10; &kgr;’(Eu3Ga5O12) =12.46±0.05; &kgr;’(Sm3Ga5O12) =12.55±0.03; &kgr;’(Nd3Ga5O12) =12.59±0.12; &kgr;’(Y3Sc2Ga3O12) =12.94±0.03; &kgr;’(Sm3Sc2Ga3O12) =13.67±0.04; and &kgr;’(La2.66Lu2.66Ga2.66O12) =14.40±0.03. The dielectric polarizability of Ga2O3derived from the dielectric constants of these and other Ga compounds is 8.80±0.14 A˚3. The agreement between measured dielectric polarizabilities as determined from the Clausius–Mosotti equation and those calculated from the sum of oxide polarizabilities according to &agr;D(mineral) =&Sgr;&agr;D(oxides) for six aluminum garnets and twelve gallium garnets is ∼1%.

ISSN:0021-8979    

DOI:10.1063/1.345026

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is known experimentally that illumination conditions can significantly affect the spectral response behavior of hydrogenated amorphous silicon (a‐Si:H) Schottky barrier detector and solar cell structures. This behavior is examined for the first time using a first‐principles numerical analysis to explore the repercussions of the relative intensities and absolute intensities of the bias light and the monochromatic light. It is demonstrated that to avoid the experimental difficulty of an ill‐defined spectral response, which can arise when lock‐in detection is used, the bias light intensity should be an order of magnitude larger than the monochromatic light intensity. More importantly, the numerical modeling demonstrated that spectral response can fundamentally depend on illumination conditions due to field redistribution and recombination redistribution. It is further shown that these redistributions depend on the homogeneity of the intrinsic absorber layer; that is, the behavior with bias light is found to be different if a thin surface layer is postulated to exist at the front of the intrinsic layer. It is also demonstrated that the spectral response can be greater in the shorter wavelengths for materials with a higher midgap density of states. This result can explain the experimentally observed effects of prolonged light soaking.

ISSN:0021-8979    

DOI:10.1063/1.345027

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effects of several reducing and oxidizing etches on CdTe surfaces have been characterized by photoluminescence. For excitation, several lines from three different types of gas lasers, emitting at 325 nm (He‐Cd laser), 488 nm (argon‐ion laser), and 632.8 nm (He‐Ne laser) were used. The corresponding light penetration depth varied from approximately 25 to 200 nm. The analysis of the photoluminescence as a function of the depth not only allows the characterization of the type of defects created by the etching but also their location from the treated surfaces. Proper etching solutions produce surfaces with a crystalline quality comparable to that of a cleaved surface and the photoluminescence spectra do not depend on the energy of the excitation.

ISSN:0021-8979    

DOI:10.1063/1.346055

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The sputter deposition of high‐temperature superconducting thin films was studied using optical emission spectroscopy. Argon or oxygen ions generated by a Kaufman ion gun were used to sputter material from a composite target containing yttrium, barium, and copper which had been oxygen annealed. The impact of ions onto the target generates a plume of sputtered material which includes various excited‐state atoms and molecules. In these studies, optical emission is detected for all the metallic components of the film as well as for metallic oxides ejected from the target. No emission due to atomic or molecular oxygen was detected, however. Variations in sputter conditions such as changes in sputter ion energy, oxygen content of the beam, and target temperature are shown to greatly affect the emission intensity, which may correlate to the characteristics of the sputtering and the quality of the films deposited. The results suggest that optical emission from the sputtered material may be useful for real‐time monitoring and control of the sputter deposition process.

ISSN:0021-8979    

DOI:10.1063/1.345028

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effects of incoherent light rapid thermal annealing and furnace annealing of arsenic‐implanted silicon (6×1015/cm2of arsenic at 70 keV) have been studied by x‐ray photoelectron spectroscopy (XPS) and secondary‐ion mass spectrometry (SIMS). The XPS analysis revealed two chemical states of arsenic with a 0.9‐eV chemical shift of the 3dcore level, which coexisted in both the as‐implanted and annealed samples. The arsenic with a higher binding energy is interpreted as substitutional arsenic, whereas the other arsenic component is assigned as either interstitial or clustered arsenic. SIMS and XPS results also indicate that surface segregation and clustering of the implanted arsenic during annealing are enhanced by the presence of implantation‐induced structural defects.

ISSN:0021-8979    

DOI:10.1063/1.345029

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effect of low‐energy ion bombardment on the structure and properties of zirconia films deposited by reactive ion‐beam process is investigated. Bombardment of 100‐eV Ar+during film growth is shown to induce a substantial relaxation of the residual stress as a result of structural modification by the increased mobility of adatoms. Concurrently, the oxygen gettering capability, or film stoichiometry, is improved by the enhanced diffusion of oxygen on substrate surface. The structural change by thermal annealing, up to 600 °C, demonstrates that fine‐grained (200–400 A˚) cubic zirconia can be stabilized down to room temperature without alloying stabilizers. The impingement of low‐energy Ar+during film growth results in an as‐deposited film microstructure which promotes the growth of the cubic‐phase crystallites upon post‐deposition annealing as well as the texturing of film plane into (111) orientation. The refractive index and optical transmission of the zirconia films are shown to be dependent predominantly upon the oxygen content in the film and less sensitive to the improved atomic packing due to the low‐energy Ar+bombardment.

ISSN:0021-8979    

DOI:10.1063/1.345030

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Presented are the results of a systematic study of the effects of reactor pressure and rf power level on the electrical and chemical characteristics ofa‐C:H films prepared by glow discharge. Electrical resistivity has been found to increase rapidly with decreasing reactor pressure. This increase in electrical resistivity corresponded to an increase in thesp3bonding content of the film. This composition change has been attributed to increased ion bombardment energy and greater time for adatom surface migration. Electrical resistivity decreased with rf power level. Thesp2bonding content of the film decreased while thesp3bonding content increased with rf power level. The resistivity change and corresponding composition change could not be explained with the present model.

ISSN:0021-8979    

DOI:10.1063/1.345031

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Porous silicon and its oxide can be converted into porous silicon oxynitrides by ammonia heat treatment. For example, ammonia treatment at 1000 °C for 1 h following 850 °C, 30‐min steam oxidation of porous silicon can result in up to 40 at. % nitrogen in the porous oxynitrides. These porous silicon oxynitrides are compositionally more uniform than ammonia‐nitrided thermal oxides which exhibit nitrogen buildup at the oxide layer interfaces. However, the order of the oxidation and nitridation treatment matters: nitrided oxidized porous silicon exhibits higher electrical breakdown strength than nitrided porous silicon or oxidized nitrided porous silicon.

ISSN:0021-8979    

DOI:10.1063/1.346077

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A thermocouple‐instrumented wafer was used to monitor the wafer temperature during chemical vapor deposition of a polycrystalline‐silicon layer in a lamp‐heated rapid thermal processor. The temperature of the oxidized silicon substrate varies by more than 100 °C as the polycrystalline‐silicon layer is deposited because the reflectivity of the sample changes with increasing thickness of the deposited layer. Cross‐section transmission electron microscopy shows that when the temperature decreases below the polycrystalline‐to‐amorphous transition temperature during deposition, a phase change occurs in the structure of the deposited film. The change in temperature qualitatively corresponds to the change in reflectivity as a function of silicon film thickness calculated from a simple model.

ISSN:0021-8979    

DOI:10.1063/1.345032

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Laser‐induced chemical vapor deposition (LCVD) of GaAs allows deposited film to trace the path of the laser beam, thus making it attractive for several applications. However the localized thermal expansion resulting from the laser‐induced temperature rise has to be elastically accomodated in order to prevent lattice defects in the LCVD film. We report on the growth conditions that can be allowed without the occurrence of plastic deformation in the epitaxial films. A model is presented to explain the thermal expansion induced distortion during the deposition process and is compared with experimental results.

ISSN:0021-8979    

DOI:10.1063/1.345033

出版商:AIP    

年代:1990

数据来源: AIP