摘要:

Measurements of the temperature dependence of resistivity and Hall coefficient in cobalt‐doped silicon show a donor level 0.40 eV from the valence band and an acceptor level 0.53 eV from the conduction band. These levels appear to be due to different charge states of the same center. Absorption and photoconductivity measurements support these determinations. Closed tube diffusions of silicon wafers on which cobalt has been evaporated result in maximum concentrations of electrically active cobalt of about 3×1014cm−3.

ISSN:0021-8979    

DOI:10.1063/1.1658663

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An examination of the current‐voltage characteristics of gold and palladium surface barriers on degenerate zinc oxide has been made. Both chemically prepared and cleaved surfaces were studied. The current conduction mode is shown to be thermionic‐field emission at room temperature and to be pure field emission at liquid‐nitrogen temperatures. The voltage dependence of the current is in good agreement with theory. The observed current magnitudes in both current modes were approximately one‐tenth that calculated by simple theory.

ISSN:0021-8979    

DOI:10.1063/1.1658664

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Positive identification of the &Ggr; andXconduction‐band minima in InGaP has been made by performing hydrostatic‐pressure experiments on forward‐biasedp‐njunction diodes. The &Ggr; andXvalleys are coincident in energy at a composition of In0.37Ga0.63P, and the corresponding bandgap is (2.17±0.02) eV at 300°K. The indirect bandgapEXin InP is inferred from the measurements to be 2.0 eV at 300°K. In addition, the pressure coefficients of the direct and indirect bandgaps, ∂E&Ggr;/∂Pand ∂EX/∂P, respectively, have been measured at various In(1−x)GaxP compositions. For InP, ∂E&Ggr;/∂Pis 8.7×10−3eV/kbar and this coefficient increases to 13×10−3eV/kbar for compositions close to In0.5Ga0.5P. On the other hand, ∂EX/∂P= −1.25×10−3eV/kbar for GaP and shows little change for compositions in the range 0.4<x<1. The deformation potential is 5.7 eV for the &Ggr; valley in InP, and increases to about 9 eV for direct bandgap ternary compositions.

ISSN:0021-8979    

DOI:10.1063/1.1658665

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Various analyses have been performed in the past for transient photoconductivity decay in the presence of trapping. One which is potentially of great use, performed by Baicker, yields both trap concentration and energy‐level position from transient decay measurements performed at a single temperature. (With the usual analyses, temperature variation measurements are required to determine energy‐level position.) Comparison between this and other analyses is performed, and criteria are developed to determine the validity of Baicker's solution. Several sets of data are presented, of which those for one trapping level meet the stated criteria, while the others do not. The discrepancy arises because of the use by Baicker of the condition of thermal equilibrium between the traps and the minority carrier band. The most interesting data presented are probably those for certain irradiated and unirradiated silicon samples which display trapping above room temperature, and show an apparent activation energy of ∼1.6 eV, substantially larger than the silicon bandgap. Such a strong dependence is partially explained using Baicker's analysis. Data for irradiated silicon and germanium are also given, including trap annealing for gamma‐irradiated Sb‐doped germanium.

ISSN:0021-8979    

DOI:10.1063/1.1658666

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A computer‐aided analysis of the transport mechanism for holes in polycrystalline germanium films indicates that the density of dislocation lines obeys the relationN=NC[1+&bgr;D exp(−a/&dgr;D)],whereNC, &bgr;D, and &dgr;Dare constants determined by experimental growth conditions. The film thickness isa. The energy bands are bent down at each surface withuB≃−10 anduS≃−7 in accordance with the surface scattering theory developed by Schrieffer and Greene, Frankl, and Zemel.

ISSN:0021-8979    

DOI:10.1063/1.1658667

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Experiments utilizing explosives with and without flyer plates have been used to determine the shock compression properties of shoal granite. High‐speed framing camera records were used to determine the free surface angles which occur in wedge‐cut samples upon the emergence of the resulting shock waves. The shock equations are given for the oblique geometry. Previously observed yield point data are used to obtain the Hugoniot of shoal granite in the range between 0 and 400 kbars.

ISSN:0021-8979    

DOI:10.1063/1.1658668

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The rare‐earth orthoferrites form a class of optical materials having intrinsically good transmission in the infrared between about 1.3 and about 8 &mgr;. In thin sections they have enough transparency to be useful in the visible region. Optical absorption loss can be less than &agr;=0.5 cm‐−1in the infrared, but Fe valence changes can reduce the transparency drastically. Doping experiments with Sn, Bi, Sb, Mg, and H+are reported and their effect on optical transparency is given.

ISSN:0021-8979    

DOI:10.1063/1.1658669

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The spectral emissivity &egr;&lgr;of tantalum for &lgr;=0.645 &mgr; and &lgr;=0.546 &mgr; has been measured by using a De Vos blackbody in ultrahigh vacuum. Changes of the emissivity with heat treatment are related to changes in surface structure, and the reproducibility of results is demonstrated by making measurements on two different blackbodies of identical construction that have been subjected to similar heat treatment. The data presented are compared to previously published results. It is found that &egr;0.645&mgr;between 1100° and 1700°K for tantalum that is not heated above 1700°K ranges from 0.420 to 0.411; that &egr;0.645&mgr;between 1100° and 2400°K for tantalum that is heat treated one hour at 2450°K ranges between 0.394 and 0.370; and that &egr;0.546&mgr;in the latter temperature interval, also for heat‐treated tantalum, ranges from 0.456 to 0.423.

ISSN:0021-8979    

DOI:10.1063/1.1658670

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Intense electric fields found in the beam‐plasma interface of Burnout V give rise to satellite spectra of the helium 23P‐43D,3Ftriplet (4471 Å), and the 21P‐41D,1Fsinglet (4922 Å) emission lines. Electric‐field strengths increasing from near zero on the magnetic axis to about 7 kV cm−1at 1 cm, and then decreasing to less than 2 kV cm−1at 2‐cm radial distance are found. An Abel inversion giving intensity of the satellite lines as a function of plasma radius together with displacement and intensity of &pgr; and &sgr; components in the Zeeman structure of the satellites gives the electric‐field strength and implies that the direction of the electric field is perpendicular to the magnetic axis.

ISSN:0021-8979    

DOI:10.1063/1.1658671

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Retarding field measurements were taken on thin films (10–−‐100 Å) of Au evaporated on an Ir (111) surface. In the range of 0–5 eV the current‐vs‐voltage plots exhibited a decaying periodic variation in amplitude. The amplitude and period of the variations both decreased with film thickness. This interference phenomenon is interpreted as being due to electron reflection occurring at both the film‐vacuum and the film‐substrate interfaces. Measurements of the period as a function of film thickness agree well with a simple free‐electron picture for the phase shift experienced by electrons traversing the film, giving an effective inner potential of 16 eV for Au. From the temperature dependence of the energy at which maxima and minima occur the thermal expansion coefficient for the films is determined. Also, estimates of the mean‐free path for electrons in the film are obtained from the decay of the variation amplitude with thickness. Values obtained for both these quantities are consistent with previously published values.

ISSN:0021-8979    

DOI:10.1063/1.1658672

出版商:AIP    

年代:1970

数据来源: AIP