| 1. |
- He, Z Q, et al.
(författare)
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As overlayer on GaAs(110) studied with photoemission
- 1995
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 52:23, s. 16602-16607
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Tidskriftsartikel (refereegranskat)abstract
- As-terminated GaAs(110) surfaces were prepared on ex situ cleaved substrates by molecular-beam epitaxy. The surface stoichiometry was controlled by postgrowth As deposition. Photoemission from a surface covered with a monolayer As was investigated in detail using synchrotron radiation. Two different surface components were found in core-level spectra, which are interpreted as due to adatoms bonding to the surface anions and cations. In the valence-band spectra several surface states were identified, in analogy with previous reports on the isoelectronic Sb/GaAs(110) system. The polarization dependence is not the same, however, which leads us to the conclusion that the adlayer bonding mechanisms are different in the two cases.
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| 2. |
- He, Z Q, et al.
(författare)
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Band structure evolution in InAs overlayers on GaAs(110)
- 1996
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Ingår i: Applied Surface Science. - 0169-4332 .- 1873-5584. ; 104, s. 608-614
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Tidskriftsartikel (refereegranskat)abstract
- An angle-resolved photoemission study of MBE grown InAs/GaAs(110) hetero-structures was carried out to investigate the establishment of valence bands as a function of overlayer thickness. The valence band spectra were found to change gradually up to thicknesses well above 10 nm. The data are interpreted in terms of excitations within the overlayer from a combination of substrate and overlayer initial states, the former tailing into the overlayer.
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| 3. |
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| 4. |
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| 5. |
- Li, Q, et al.
(författare)
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A delta MYWE algorithm for parameter estimation of noisy AR processes
- 1996
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Ingår i: IEEE TRANSACTIONS ON SIGNAL PROCESSING. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. ; 44:5
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this correspondence, we develop a delta-operator-based modified Yule-Walker equation algorithm (MYWE) for parameter estimation of a noisy autoregressive (AR) process. The methodology in developing this new algorithm is similar to the previous works on
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| 6. |
- Varekamp, P R, et al.
(författare)
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Angle-resolved photoemission spectroscopy of the 1x1 ordered overlayers on iodine-saturated GaAs(001) and InAs(001)
- 1996
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 352, s. 387-390
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Tidskriftsartikel (refereegranskat)abstract
- Angle-resolved valence band photoelectron spectra are collected from 1 X 1 ordered overlayers on I-2-saturated GaAs(001)-4 x 1, -c(2 X 8), and InAs(001)-c(8 x 2). A high-intensity dispersive surface state, located approximately 4.4 eV below the valence band maximum, is observed in each case. The state passes through an open lens in the projected bulk density of states and disperses symmetrically around the surface Brillouin zone edge. For all surfaces studied, the state is stronger when excited with the electric field polarized in the [110], as compared to the <(1)over bar 10>], azimuth. Since the state is independent of the termination of the initial surface, and since iodine bonds primarily to the outermost element, the state must result from delocalization of the electron states in the overlayer, and is not related to bonding with the substrate.
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| 7. |
- Varekamp, P R, et al.
(författare)
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Reaction of I-2 with the (001) surfaces of GaAs, InAs, and InSb .2. Ordering of the iodine overlayer
- 1996
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 54:3, s. 2114-2120
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Tidskriftsartikel (refereegranskat)abstract
- The overlayer formed by the reaction of molecular iodine (I-2) with GaAs(001), InAs(001), and InSb(001) is investigated with synchrotron soft x-ray photoelectron spectroscopy (SXPS) and scanning tunneling microscopy (STM). Two components, separated by about 0.5 eV, are present in all of the I 4d SXPS spectra. At very low iodine coverages, the high binding energy (BE) component dominates. When the iodine coverage saturates, however, the two components have equal intensities. In contrast to GaAs and InAs, exposure of InSb(001)-c(8x2) to additional I-2 results in a further increase of the relative intensity of the low-BE component. STM images of I-2 covered InSb(001)-c(8x2) directly reveal the ordering in the overlayer. Islands are visible for submonolayer coverages, suggesting that adsorption occurs via a mobile precursor state. STM images feature occupies a 1x1 unit cell with the same spacing as bulk-terminated InSb(001). The other feature has a coverage of similar to 1/3 ML and is arranged in pairs oriented along the [110] azimuth.
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