Nitrogen States In Ga(as,p) And The Long-range, Short-range Model: A Systematic Study

The long-range, short-range model of the nitrogen isoelectronic impurity in Ga(As,P) is discussed in terms of the results of recent photoluminescence and lifetime measurements. The predictions of the theory are shown to depend sensitively upon the strength of the coupling among the states produced separately by the long- and short-range parts of the potential: The strength of the coupling reflects the specific model of potential used in all cases treated. Strong coupling yields theoretical energies whose general composition dependence mirrors the features of the data. The effect of consideration of the L-conduction-band minima is smaller. Determination of potential parameters from experimental energies indicates a range 20-25. Luminescence calculations require an accurate treatment of the continuum contribution. Predictions of the theory are in good agreement with available data. Inclusion of L indicates the existence of an excited nitrogen state in GaP. No internal inconsistencies in the theory are found. © 1980 The American Physical Society.2183478349

Theory Of Bound States Induced By Disorder And Isoelectronic Potentials: Ga(as,p):n

A theory is presented in which bound states arising from a combination of long-range and short-range isoelectronic potentials are shown to account for recent experimental data in Ga(As,P):N. These results alter our physical picture in this system. Numerical calculations agree with experiment. They indicate that the long-range potential may correspond to a deformation potential which arises from a uniform, slowly varying dilation of the lattice constant in the region of the nitrogen atom. Analysis of experimental data suggests an expansion of 0.9% of the lattice constant. © 1977 The American Physical Society.15280281

Nitrogen States In Ga(as,p) And The Koster-slater Model

Recent photoluminescence data in Ga(As,P): N as a function of P fraction, x, indicates the existence of three states associated with isolated nitrogen impurities for x0.47. For x0.47, however, only one state has been measured with photoluminescence. This state, NX, has been described by a Koster-Slater model in recent work and the numerical agreement between the predictions of these calculations and the data was thought to support the model. We show that the model is extremely sensitive to parameters used in calculations and that such numerical agreement does not justify the model. The only support for the Koster-Slater model is the observation of a single state. Recent electromodulation data indicate the existence of two states. © 1978 The American Physical Society.17292492

Corelike Nature Of The Pd Mvv Shift In Pd-based Alloys

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We present arguments based on the formal similarity of the Cini and Koster-Slater models to show that, in alloys, iVV Auger spectra that are significantly distorted from the quasiatomic form may present kinetic-energy shifts that do not correspond to the quasiatomic situation, even when the origin of the terms of the line shape is quasiatomic. By comparing measured shifts of the Pd M5VV and L3M4,5M4,5 true core-level spectrum in Pd-Cu alloys, we verify this conclusion in this case. The corresponding experimental shifts of Ag in Pd-Ag alloys are, however, closely related, as expected from the quasiatomic nature of the Ag MVV spectrum. In alloy studies, therefore, true core-level Auger kinetic-energy shifts should be employed. © 1992 The American Physical Society.4524138991390303/12595-7; FAPESP; São Paulo Research FoundationFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

X-ray Photoemission Spectroscopy Of Pt-cu: A Canonical Alloy

The possibility of employing x-ray photoemission valence-band spectra in a quantitative fashion for elucidation of valence-electron structure changes induced by alloying is examined. The special, or "canonical," property of Pt1-xCux, that one of the components, Pt, displays no measurable core-level shift, permits extraction of such changes from core-level and valence-band data alone. A relation between the d-resonant level shifts and the centroid of the valence-band spectra is derived and comparison of the centroid and core-level shifts leads to the desired information. The analysis indicates that there is no charge transfer in the system and that only Cu has significant valence occupation changes upon alloying, corresponding to dehybridization. Furthermore, information regarding Fermi-energy shifts is extracted and not required as input the results suggest that the shifts of the Fermi levels cannot be identified with those of the work functions as in other work. Model calculations indicate that dehybridization is to be expected as an "antihybridization" effect for a narrow d-band metal in a wide d-band one. © 1981 The American Physical Society.2373177318

Electronic Structure Information Of Metals And Alloys From Auger And Photoemission

We report some of the results of extensive experimental and theoretical studies by our group of the XPS and Auger spectra of the transition and noble metals and some of their alloys: we concentrate on those aspects of the spectra which regard the determination of electronic structure. Consideration of the Auger kinetic energies yields insight into screening mechanisms and suggests methods for extracting electronic structure changes in alloys from XPS and XAES shifts. We demonstrate that the charge transfer in a number of alloys (AuPd, CuPd, AgPd, AuCu, AgAu and CuNi) appears to be negligible (i.e., on the order of hundredths of electrons/atom). Examples (i.e., AuZn, AuMg, AuPd, AgPd and CuNi) of the results for the d- and sp-electron occupations are given. © 2004 Elsevier B.V. All rights reserved.2281-2 SPEC. ISS.137143Kleiman, G.G., Landers, R., (1998) J. Electron. Spectrosc. Relat. Phenom., 88-91, p. 435Kleiman, G.G., Landers, R., De Castro, S.G.C., (1995) J. Electron. Spectrosc. Relat. Phenom., 72, p. 199Kleiman, G.G., Landers, R., (1995) J. Electron. Spectrosc. Relat. Phenom., 76, p. 319Kleiman, G.G., (1982) 11/12 Appl. Surf. Sci., p. 730Kleiman George, G., (1995) Phys. Status Solidi B, 192, p. 503Kleiman, G.G., (1999) J. Electron. Spectrosc. Relat. Phenom., 100, p. 17Kleiman, G.G., (2002) J. Electron. Spectrosc. Relat. Phenom., 127, p. 53Lang, N.D., Williams, A.R., (1977) Phys. Rev. B, 16, p. 2408Lang, N.D., Williams, A.R., (1979) Phys. Rev. B, 20, p. 1369Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1992) Phys. Rev. B, 45, p. 13899Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1993) Surf. Sci., 287-288, p. 794Cini, M., (1977) Solid State Commun., 24, p. 681Cini, M., (1978) Phys. Rev. B, 17, p. 2486Sawatzky, G.A., (1977) Phys. Rev. Lett., 39, p. 504noteMårtensson, N., Johansson, B., (1980) Phys. Rev. Lett., 45, p. 482Mårtensson, N., Hedegard, P., Johansson, B., (1987) Phys. Scripta, 29, p. 154Mårtensson, N., Nyholm, R., Johansson, B., (1980) Phys. Rev. Lett., 45, p. 754Johansson, B., Mårtensson, N., (1980) Phys. Rev. B, 21, p. 4427Williams, A.R., Lang, N.D., (1978) Phys. Rev. Lett., 40, p. 954Kleiman, G.G., Landers, R., Nascente, P.A.P., De Castro, S.G.C., (1992) Phys. Rev. B, 46, p. 4405Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1991) Phys. Rev. B, 44, p. 3383Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1992) J. Vac. Sci. and Technol. a, 10, p. 2839Kleiman, G.G., De Castro, S.G.C., Rogers, J.D., Sundaram, V.S., (1982) Solid State Commun., 43, p. 257Rogers, J.D., Sundaram, V.S., Kleiman, G.G., De Castro, S.G.C., Douglas, R.A., Peterlevitz, A.C., (1982) J. Phys. F, 12, p. 2097Hohenberg, P., Kohn, W., (1964) Phys. Rev., 136, p. 864Kohn, W., Sham, L.J., (1965) Phys. Rev., 140, p. 113Thomas, T.D., Weightman, P., (1986) Phys. Rev. B, 33, p. 5406Gelatt Jr., C.D., Ehrenreich, H., (1974) Phys. Rev. B, 10, p. 398Mueller, F.M., (1967) Phys. Rev., 153, p. 659Kleiman, G.G., Landers, R., De Castro, S.G.C., Rogers, J.D., (1991) Phys. Rev. B, 44, p. 8529Nascente, P.A.P., De Castro, S.G.C., Landers, R., Kleiman, G.G., (1991) Phys. Rev. B, 43, p. 4659Landers, R., De Castro, S.G.C., Kleiman, G.G., (1994) J. Electron. Spectrosc. Relat. Phenom., 68, p. 145Winter, H., Durham, P.J., Temmerman, W.M., Stocks, G.M., (1986) Phys. Rev. B, 33, p. 2370Magri, R., Wei, S.H., Zunger, A., (1990) Phys. Rev. B, 42, p. 11388Johnson, D.D., Pinski, F.J., (1993) Phys. Rev. B, 48, p. 11553Cole, R.J., Gregory, D.A.C., Weightman, P., (1994) Phys. Rev. B, 49, p. 5657Cole, R.J., Matthew, J.A.D., Weightman, P., (1995) J. Electron. Spectrosc. Relat. Phenom., 72, p. 255Barbieri, P.F., De Siervo, A., Carazzolle, M.F., Landers, R., Kleiman, G.G., (2004) J. Electron. Spectrosc. Relat. Phenom., 135, p. 11

On Directly Measuring Relative Fermi Energies Of Noble Metals And Their Alloys

We present the first evidence of direct measurement of relative Fermi energies in alloys and between pure metals. From applying the "atomic" concept of core hole final state screening, the Auger energy shift of noble metal A equals EF A-EF(x). High resolution Auger shifts in P1-x tCux,AuxCu1-x and AuxAg1-x demonstrate experimental verification of this simple relation. We find EF CuEF Au ≅ - 0.2 eV, and EF Pt ≅ EF Cu and EF Ag ≅ EF Au. © 1981.391111711174Ehrenreich, Schwartz, (1976) Solid State Physics, 31, p. 150Sellmyer, (1978) Solid State Physics, 33, p. 83Lang, Kohn, (1971) Phys. Rev., 3 B, p. 1215Lang, (1973) Solid State Physics, 28, p. 225Eastman, (1970) Phys. Rev., 2 B, p. 1Rivière, (1969) Solid State Surface Science, 1. , M. Green, Dekker, New YorkGelatt, Ehrenreich, (1974) Phys. Rev., 10 B, p. 398Watson, Hudis, Perlman, (1971) Phys. Rev., 4 B, p. 4139Lang, Williams, (1977) Phys. Rev., 16 B, p. 2408Williams, Lang, (1978) Phys. Rev. Lett., 40, p. 954Lang, Williams, (1979) Phys. Rev., 20 B, p. 1369Martensson, Johansson, Valence-Band and Core-Level Satellites in Nickel and Related Elements (1980) Physical Review Letters, 45, p. 482Johansson, Martensson, (1980) Phys. Rev., 21 B, p. 4427Martensson, Nyholm, Johansson, (1980) Phys. Rev. Lett., 45, p. 745Kleiman, Sundaram, Rogers, Summary Abstract: Auger shifts and characterization of electronic structure of alloys containing noble metals (1981) Journal of Vacuum Science and Technology, 18, p. XXXXKowalczyk, Pollak, McFeely, Ley, Shirley, (1973) Phys. Rev., 8 B, p. 2387Powell, Mandl, (1972) Phys. Rev. Lett., 29, p. 1153Yin, Tsang, Adler, Yellin, (1972) J. Appl. Phys., 43, p. 3464Weightman, Roberts, Johnson, (1975) J. Phys., 8 C, p. 550Roberts, Weightman, Johnson, (1975) J. Phys., 8 C, p. 1301Antonides, Janse, Sawatsky, (1977) Phys. Rev., 15 B, p. 1669Heine, (1967) Phys. Rev., 153, p. 673Hubbard, (1967) J. Proc. Phys. Soc., 92, p. 921V.S. Sundaram, J.D. Rogers and R. Landers (J. Vac. Sci. Tech., in press)Powell, (1973) Phys. Rev. Lett., 30, p. 1179Kleiman, Sundaram, Barreto, Rogers, (1979) Sol. St. Commun., 32, p. 919Kleiman, Sundaram, Rogers, de Moraes, (1981) Phys. Rev., 23 B, p. 3177Sundaram, Rogers, de Moraes, Kleiman, X-ray photoemission lineshapes and energies in PdxCu1-x (1981) Journal of Physics F: Metal Physics, 11, p. XXXXKleiman, (1981) Proceedings of the Second International Conference of Solid Films and Surfaces, , College Park, Maryland(1980) First Latin American Symposium on Surface Physics, , Niteroi, Brasi

Shake-up Satellites In High Energy Auger Spectra Of The 4d Metals

Interpretation of the satellites of the Cu L2,3M4,5M4,5 has involved considerable controversy in recent years. Reaching unambiguous conclusions is impeded by the contribution of Coster-Kronig (CK) transitions, requiring considerable experimental investigation before clarifying the relative roles of shake-up and CK processes. The L2,3M4,5M4,5 spectra of Ag, Pd and Rh excited by bremsstrahlung also have satellite features and manifest the following experimental systematics: both the L3 and L2 losses are displaced the same amount relative to their respective main peaks and their shapes are approximately the same; there seems to be little CK contribution; and comparison with alloy spectra indicate the intrinsic nature of the losses, consistent with energy loss measurements. We demonstrate that the satellite relative positions and lineshapes are consistent with the spectator vacancy interpretation, so that they appear to correspond basically to broadened, displaced "images" of the corresponding main spectra. It seems that the satellites are almost entirely caused by intra-atomic shake-up processes; the "image" nature of their lineshapes resembles that of extrinsic losses in other metals.357-358251254Kleiman, G.G., Landers, R., Nascente, P.A.P., De Castro, S.G.C., (1992) Phys. Rev. B, 46, p. 1970Mariot, J.-M., Ohno, M., (1986) Phys. Rev. B, 34, p. 2182Yoshii, K., Baba, Y., Sasaki, T.A., (1995) J. Electron Spectrosc., 72, p. 107Landers, R., Nascente, P.A.P., De Castro, S.G.C., Kleiman, G.G., (1992) J. Phys. Condens. Matter, 4, p. 5881Landers, R., Nascente, P.A.P., De Castro, S.G.C., Kleiman, G.G., (1993) Surf. Sci., 287-288, p. 802Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1993) Surf. Sci., 287-288, p. 798Landers, R., Kleiman, G., De Castro, S.G.C., (1995) J. Electron Spectrosc., 72, p. 211Kleiman, G.G., Landers, R., De Castro, S.G.C., (1994) J. Electron Spectrosc., 68, p. 329Kleiman, G.G., Landers, R., De Castro, S.G.C., (1994) Phys. Rev. B, 49, p. 2753Lang, N.D., Williams, A.R., (1977) Phys. Rev. B, 16, p. 2408Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1992) Phys. Rev. B, 45, p. 13899Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1991) Phys. Rev. B, 44, p. 3383Kleiman, G.G., Landers, R., De Castro, S.G.C., Nascente, P.A.P., (1992) J. Vac. Sci. Technol. A, 10, p. 2839Kleiman, G.G., Landers, R., Nascente, P.A.P., De Castro, S.G.C., (1992) Phys. Rev. B, 46, p. 4405Kleiman, G.G., Landers, R., Nascente, P.A.P., De Castro, S.G.C., (1993) Surf. Sci., 287-288, p. 794Kleiman, G.G., (1993) J. Phys. Condens. Matter, 5, p. 1Kleiman, G.G., Landers, R., De Castro, S.G.C., Rogers, J.D., (1991) Phys. Rev., 644, p. 8529Kleiman, G.G., (1982) Appl. Surf. Sci., 11-12, p. 730Nascente, P.A.P., De Castro, S.G.C., Landers, R., Kleiman, G.G., (1991) Phys. Rev. B, 43, p. 4659Wagner, C.D., Taylor, J.A., (1980) J. Electron Spectrosc., 20, p. 83Sundaram, V.S., Rogers, J.D., Landers, R., (1981) J. Vac. Sci. Technol. A, 19, p. 117Condon, E.U., Shortley, G.H., (1963) The Theory of Atomic Spectra, , Cambridge University, LondonKleiman, G.G., Landers, R., De Castro, S.G.C., unpublishedLanders, R., Kleiman, G.G., De Castro, S.G.C., J. Electron Spectrosc., , in pressNyholm, R., Mårtensson, N., (1980) J. Phys. C, 13, pp. L279Mårtensson, N., Nyholm, R., (1981) Phys. Rev. B, 24, p. 7121noteMartensson, N., Johansson, B., (1983) Phys. Rev. B, 28, p. 3733Drube, W., Lessmann, A., Materlik, G., (1992) Jpn. J. Appl. Phys., 32, p. 17

Noble Metal Auger Spectroscopy As A Probe Of Electronic Structure: Mapping Fermi Energies In Trimetallic Alloys

XPS binding energy shifts in alloys are sensitive to valence occupation changes. Since binding energies are defined relative to the Fermi energy, exploitation of this property of the shifts has been hampered by ignorance of relative Fermi energies. Application of the quasiatomic model of screening shows that, for noble metal atom N in bimetallic alloy AxN1-x, in the absence of charge transfer, the Auger kinetic energy shift, ΔKN (x) ≅ -ΔEFN (x), the Fermi energy relative to that of pure metal N. Study of a number of such alloys demonstrates the validity of the relation, allowing one to adduce little charge transfer and, for Au-Pd, to determine valence occupation changes. These results suggest the possibility of probing the relative Fermi energy in a general random alloy by measuring the Auger shift of a noble metal impurity. Validity of this relation implies that the difference between the Auger shifts of different impurities should be constant independent of concentration. Here we report XPS and Auger spectroscopy measurements of trimetallic alloys with low concentrations of noble metal N (N = either Ag or Cu). Ag, Cu and Au Auger shifts in AuxPdyNz alloys are consistent with these ideas and with previous results. © 1991.68C145149Kleiman, (1982) Applications of Surface Science, 11 (12), p. 730Kleiman, Landers, de Castro, Rogers, (1991) Phys. Rev. B, 44, p. 8529Nascente, de Castro, Landers, Kleiman, (1991) Phys. Rev. B, 43, p. 4659Thomas, Weightman, (1986) Physical Review B, 33, p. 5406Chou, Perlman, Watson, (1976) Phys. Rev. B, 14, p. 3248Kleiman, Sundaram, Rogers, de Moraes, (1981) Phys. Rev. B, 23, p. 3177Sundaram, Rogers, Landers, (1981) J. Vac. Sci. Technol., 19, p. 117Kleiman, de Castro, Rogers, Sundaram, (1982) Solid State Commun., 43, p. 257Rogers, Sundaram, Kleiman, de Castro, Douglas, Peterlevitz, (1982) J. Phys. F, 12, p. 2097Kleiman, Landers, de Castro, Nascente, (1991) Phys. Rev. B, 44, p. 3383Kleiman, Landers, de Castro, Nascente, (1992) Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 10, p. 2839Kleiman, Landers, Nascente, de Castro, (1992) Phys. Rev B, 46, p. 4405Kleiman, Landers, Nascente, de Castro, (1993) Surface Science, 287 (288), p. 798Landers, Nascente, de Castro, Kleiman, (1992) J. Phys.: Condens. Matter, 4, p. 5881Landers, Nascente, de Castro, Kleiman, (1993) Surface Science, 287 (288), p. 802R. Landers, S.G.C. de Castro and G.G. Kleiman (unpublished)Steiner, Hüfner, M»rtensson, Johansson, (1981) Solid State Commun., 37, p. 73M»rtensson, Nyholm, Calén, Hedman, (1981) Physical Review B, 24, p. 1725Watson, Hudis, Perlamn, (1971) Phys. Rev. B, 4, p. 4139Kleiman, Sundaram, Rogers, (1981) Solid State Commun., 39, p. 1171Kleiman, Sundaram, Rogers, (1981) Journal of Vacuum Science and Technology, 18, p. 58

L2,3m4,5m4,5 X-ray-excited Auger-electron Spectra Of Ag

We have investigated the L2,3M4,5M4,5 Auger spectra of Ag excited with bremsstrahlung. The main experimental spectra are in good agreement with atomic-multiplet-structure calculations in which the initial state is treated in jj coupling and the final state in the intermediate coupling scheme. Anomalous loss structures appear at lower energies than those of the main spectra. These losses appear to be atomic in origin and are not manifest in the corresponding spectra of In, Sn, and Sb. We demonstrate that these losses are consistent with a model of d-band spectator vacancy shake-up satellites. Coster-Kronig processes present in Cu appear to be absent here. © 1994 The American Physical Society.4942753275