摘要:

The electromigration velocities of liquid metal inclusions in single‐crystal Si were found to follow an Arrhenius relationship with temperature. The activation energies and preexponential factors of liquid metal inclusions of Pd, Au, Cu, Al, Ag, Ga, In, and Sn were measured. Liquid Sb inclusions did not electromigrate. Electromigration velocities were linearly proportional to the applied electric current. Inclusions of Pd, Au, and Cu which have relatively high work functions electromigrate towards the anode while inclusions of Al, Ag, Ga, In, and Sn which have relatively low work functions electromigrate toward the cathode. The relative order of electromigration velocities within the anode‐directed group and within the cathode‐directed group can be accounted for by setting the electromigration force proportional to the difference between the work function of the metal of the inclusions and an experimentally determined null‐point work function and by considering the solubility of silicon in the inclusion.

ISSN:0021-8979    

DOI:10.1063/1.327625

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Amorphous electrodeposited thin films of nickel phosphides, containing 20 and 22 at. % P were studied by electron microscopic methods. Upon beam heating the amorphous phase transformed into Ni12P5and several other new crystalline phases, with or without additional metallic nickel. The following crystallizations from the electrodeposited Ni‐P films were observed: (1a) Amorphous Ni‐P→NixPy(Ni)+Ni. The probable values ofxandyare 5 and 2, respectively. The lattice parameters area=6.61 andc=12.31 A˚. Upon further beam heating (1a) transforms to: (1b) NixPy(Ni)+Ni→Ni3P+Ni. The body‐centered tetragonal unit cell dimensions of Ni3P area=8.93 andc=4.39 A˚. (2) Amorphous Ni‐P→Ni12P5. The unit cell of Ni12P5is again body‐centered tetragonal, witha=8.64 andc=5.07 A˚. (3) Amorphous Ni‐P→Ni3P. The hexagonal unit cell parameters area=5.00 andc=8.66 A˚. (4) Amorphous Ni‐P→Ni3P+Ni. The unit cell is again body‐centered tetragonal, like that of (1b). However, the dimensions area=6.10 andc=5.04 A˚. (5) Amorphous Ni‐P→Ni3P. The body‐centered unit cell dimension isa=6.10 A˚. The observation of such a number of crystalline phases implies that the crystallization of the amorphous Ni‐P films is more complex than expected and it must depend on a number of factors, including rates of electron beam heating, temperature gradients, and the homogeneity of the as‐deposited sample. Although the unit cell dimensions of various phases are distinct, there is an apparent geometric relationship between the magnitudes of individual unit translations. This observation indicates that the primary structures of these phases must be simple closed‐packed structures derivable from hcp, fcc, and bcc structures. Interestingly, while the transformation from the amorphous Ni‐P to the equilibrium two‐phase mixture of (1b) occurred through the crystallization of the intermediate metastable two‐phase mixture of (1a) in accordance with the Ostwald rule, the transformation from the amorphous Ni‐P to the equilibrium phases of 2, 3, 4, and 5 underwent no subsequent transformation, therefore violating the Ostwald rule.

ISSN:0021-8979    

DOI:10.1063/1.327626

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A mechanism is considered for oxide growth on an electrically isolated metal sample in the presence of an rf‐excited oxygen plasma. The assumption is made that the rate of rf oxidation is limited by transport of ionic species through the already‐formed oxide layer. Thermally activated hopping of ionic defects in the presence of electric fields due to the surface potential established by the rf discharge and modified by the space charge of the mobile ionic defects is hypothesized. The origin of the voltage across the oxide is discussed in terms of a balance between the transport of negatively charged O ions and transport of electron holes created by ion neutralization of positive ions from the plasma. This model is developed analytically and evaluated numerically by employing the continuum limit of hopping transport equations valid for the very‐high‐field limit. A three parameter fit gives excellent agreement of the theory with the published data of Greiner for the rf oxidation of lead. The fitting parameters are the voltage across the oxide film, the ionic diffusivity, and the rate at which the oxide is removed by sputtering. The resulting parameter values are shown to be in reasonable accord with available experimental data. Parametric curves are presented to illustrate the dependence of the kinetics on the various microscopic parameters. The dependence of the limiting thickness on the primary parameters is likewise presented. It is shown that the growth rate may be significantly retarded by high levels of space charge in the oxide.

ISSN:0021-8979    

DOI:10.1063/1.327627

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Investigations have been made of Al‐pSi metal‐insulator semiconductor (MIS) cells fabricated by depositing Al films onto silicon substrates with thermally grown SiO2surface films on the order of 18 A˚ thick. These studies have involved depth concentration profiling and ellipsometric measurements to understand the physical structure, electrical and optical characterization of aluminum films, and efforts to optimize an Al‐Si cell with a SiO antireflection (AR) coating. Depth concentration profiles show that the correct physical model is not Al/SiO2/Si, but Al/Al2O3(Si)/Si with the Al2O3interfacial layer being 15 A˚ thick. The Al film reduces the SiO2to yield Al2O3+Si for an interfacial film. Investigations to optimize the Al‐Si cell structure involved using optical constants measured for Al films to determine AR layer thicknesses, which maximize cell photocurrent for each Al film thickness. Analytical studies were also conducted concerning sheet resistance effects to determine the required grid design to maximize the fill factor. These analytical and experimental studies are used to project an ultimate, practical AM1 efficiency of 11–12% for Al‐pSi MIS cells based on a continuous metal front layer and a silicon resistivity of 2–5 &OHgr; cm.

ISSN:0021-8979    

DOI:10.1063/1.327628

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Previous studies have shown that the characteristics of the semiconductor‐insulator‐semiconductor (SIS) solar cell can be controlled by the thin interfacial layer. In this paper, we present the results of a theoretical investigation of the role of interface states at the SiO2‐Si interface in the ITO‐SiO2‐Si SIS solar cell. A numerical solution of the governing transport equations yields the dependence of efficiency, short‐circuit current, and open‐circuit voltage on interface state density. It is shown theoretically that occupied acceptorlike interface state lower the barrier height and thus raise the dark saturation current while lowering the open‐circuit voltage. Experimental results are presented which relate the saturation current to the process step which forms the interfacial layer and which support the model.

ISSN:0021-8979    

DOI:10.1063/1.327584

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Zinc oxide is a piezoelectric material which, in thin‐film form, is finding wide application in surface acoustic wave devices. In order to obtain good electromechanical coupling, the polycrystalline film must simulate single‐crystal properties. In this study, we report the effect of rf power on the crystallographic orientation and grain structure of reactively sputtered ZnO. Films were deposited at forward power levels ranging from 300 to 640 W on both uncoated and Al‐coated Si substrates by sputtering a ZnO target using a 75% Ar/25% O2gas mixture. The results of this study show that both film microstructure and crystallography are dependent upon the rf power level, with an increase in the amount of structural disorder occurring with increasing power. The magnitude of this effect is dependent upon the substrate. The results are discussed in terms of the average deposition rate, the relative number of Zn to ZnO ions in the plasma, monitored by glow discharge mass spectrometry, and bombardment of the growing film by secondary electrons emitted from the target.

ISSN:0021-8979    

DOI:10.1063/1.327585

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A quadrupole mass spectrometer has been utilized to study active discharges containing Cs vapor. Production of positive ions by electron impact within the mass spectrometer and subsequent secondary electron emission from cesiated surfaces produced spurious or pseudonegative ion signals which interfered with attempts to sample negative ions from the plasma. These effects may also occur in other gas discharge systems.

ISSN:0021-8979    

DOI:10.1063/1.327586

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A criterion for mode locking a semiconductor diode laser is proposed. The criterion is based on reducing the difference frequency associated with unequally spaced, longitudinal modes to a value smaller than the mode width narrowed by stimulated emission. An integrated GaAs‐GaAlAs structure that satisfies this condition is described. In addition to providing a more compact structure than the external mirror geometries previously used to generate mode‐locked pulses, the integrated composite resonator avoids the critical alignment problems and subcavity reflection limitations of an external resonator system.

ISSN:0021-8979    

DOI:10.1063/1.327587

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

We investigated the dynamic characteristics related to the transient spectra of two types of transverse‐mode stabilized GaAlAs double‐heterostructure lasers: internally‐striped‐planar (ISP) and channeled‐substrate‐planar (CSP) lasers. These lasers exhibited a linear light‐current relation, stable transverse‐mode oscillation, and dynamic response with suppressed relaxation oscillations. Several differences in their spectral behavior have been observed. The dc spectrum of the CSP laser shows a single longitudinal mode, whereas the dc spectrum of the ISP laser shows multilongitudinal modes. In the ISP laser, the transient spectrum under fast pulse modulation is nearly identical to its dc spectrum. The CSP laser shows a transient spectrum that is broader than that in cw operation. The experimental results may be explained from the differences of their device structure and waveguiding mechanisms.

ISSN:0021-8979    

DOI:10.1063/1.327588

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The scattering formalism of Gubernatis, Domany, and Krumhansl is extended to accommodate a description of inelastic scattering of elastic vibration waves. A viscoelastic scattering target is embedded in an elastic host medium. Owing to the absorptive nature of the target, besides the longitudinal and transverse scattering channels, there is also an absorption channel. By postulating the general form of viscoelastic constitutive relations, a simple prescription is arrived at for the modification of the elastic scattering formalism.

ISSN:0021-8979    

DOI:10.1063/1.327589

出版商:AIP    

年代:1980

数据来源: AIP