Dr Paul Kinsler. [Acknowledgements & Feedback]
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<> From eenpk@sun Mon Oct 6 17:07:28 1997 <> Received: from sun.leeds.ac.uk (sunserv7_le0.leeds.ac.uk [188.8.131.52]) by bloch.leeds.ac.uk (950413.SGI.8.6.12/950213.SGI.AUTOCF) via ESMTP id RAA12007 for
; Mon, 6 Oct 1997 17:07:28 +0100 <> Received: from sun.leeds.ac.uk (eenpk@eenserv1 [184.108.40.206]) <> by sun.leeds.ac.uk (8.8.5/8.8.5) with SMTP id RAA10248 <> for ; Mon, 6 Oct 1997 17:19:54 +0100 (BST) <> From: P Kinsler <> Message-Id: <email@example.com> <> Subject: confined phonon modes (fwd) <> To: eenpk <> Date: Mon, 6 Oct 1997 17:19:56 +0100 (BST) <> X-Mailer: ELM [version 2.4 PL25] <> Mime-Version: 1.0 <> Content-Type: text/plain; charset=US-ASCII <> Content-Transfer-Encoding: 7bit <> Status: RO <> <> Forwarded message: <> >From een6rwk Mon Oct 6 17:14 BST 1997 <> From: R W Kelsall <> Date: Mon, 6 Oct 97 17:14:40 BST <> Message-Id: <firstname.lastname@example.org> <> To: eenpk <> Subject: confined phonon modes <> Content-Type: text <> Content-Length: 15930 <> <> Paul; <> <> some papers from BIDS which may be worth following up. No. 5 looks particularly interesting. <> <> Rob <> <> <> <> <> <> (1) TI: SIMPLIFIED MICROSCOPIC MODEL FOR ELECTRON OPTICAL-PHONON <> INTERACTIONS IN QUANTUM-WELLS <> AU: BHATT_AR, KIM_KW, STROSCIO_MA, HIGMAN_JM <> NA: N CAROLINA STATE UNIV,DEPT ELECT & COMP ENGN,RALEIGH,NC,27695 <> USA,RES OFF,RES TRIANGLE PK,NC,27709 <> UNIV ILLINOIS,BECKMAN INST,URBANA,IL,61801 <> JN: PHYSICAL REVIEW B-CONDENSED MATTER, 1993, Vol.48, No.19, <> pp.14671-14674 <> IS: 0163-1829 <> DT: Note <> AB: A simplified microscopic model of optical phonons in <> dimensionally confined structures is formulated and applied to <> calculate electron-optical-phonon scattering rates in GaAs/AlAs <> quantum wells. For this simplified model which circumvents <> performing a complicated ab initio calculation of the force <> constants at the interface, it is demonstrated that the <> resulting dispersion relation and scattering rates for <> electron-optical-phonon interactions agree very well with those <> obtained from detailed ab initio studies. It is also shown that <> for GaAs/A]As structures, the macroscopic dielectric continuum <> model provides a good approximation to the scattering rate <> predicted by the microscopic models. <> KP: ZINCBLENDE STRUCTURE COMPOUNDS, LATTICE-DYNAMICS, GAAS/ALAS <> SUPERLATTICES, FORCE-CONSTANTS, HETEROSTRUCTURES, GAAS, <> POLARIZABILITY, SCATTERING, SYSTEMS <> <> <> (3) TI: HOT-ELECTRON RELAXATION VIA THE EMISSION OF GAAS OPTICAL MODES <> AND ALAS INTERFACE MODES IN GAAS ALAS MULTIQUANTUM WELLS <> AU: OZTURK_E, CONSTANTINOU_NC, STRAW_A, BALKAN_N, RIDLEY_BK, <> RITCHIE_DA, LINFIELD_EH, CHURCHILL_AC, JONES_GAC <> NA: UNIV ESSEX,DEPT PHYS,COLCHESTER CO4 3SQ,ESSEX,ENGLAND <> UNIV CAMBRIDGE,CAVENDISH LAB,CAMBRIDGE CB3 0HE,ENGLAND <> JN: SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 1994, Vol.9, No.5 SS, <> pp.782-785 <> IS: 0268-1242 <> AB: We demonstrate via hot-electron photoluminescence and high- <> temperature mobility measurements the importance of the AlAs <> interface mode in the energy relaxation of electrons in <> GaAs/AlAs multi-quantum wells. A corresponding investigation of <> a similar GaAs/Al0.24Ga0.76As system illustrates that this is <> not the case for AlGaAs barrier devices where GaAs modes are <> the dominant energy relaxation process. The importance of the <> AlAs interface mode is not simply related to its intrinsic <> scattering rate but also to its shorter lifetime (compared with <> GaAs modes). Hot-phonon effects are therefore crucial to a full <> understanding of the experimental data. <> KP: DOUBLE HETEROSTRUCTURES, PHONON INTERACTIONS, TRANSPORT <> <> (4) TI: ENERGY AND MOMENTUM RELAXATION RATES FOR CONFINED AND INTERFACE <> MODES IN QUANTUM-WELL STRUCTURES <> AU: GUPTA_R, RIDLEY_BK <> NA: UNIV ESSEX,DEPT PHYS,WIVENHOE PK,COLCHESTER CO4 <> 3SQ,ESSEX,ENGLAND <> JN: SEMICONDUCTOR SCIENCE AND TECHNOLOGY, 1994, Vol.9, No.5 SS, <> pp.753-755 <> IS: 0268-1242 <> AB: In GaAs/AlAs quantum well structures both the confined GaAs <> optic phonon and the AlAs interface polariton (IP) mode <> contribute to the energy and momentum relaxation of hot <> electrons. It has been shown that in real multiple quantum well <> structures elastic scattering of phonons can lead to a non- <> drifting population of hot phonons, which results in a <> suppression of the high-field electron drift velocity. The <> consequences for device application are obvious. The non-drift <> of the mode is determined by the relative magnitudes of its <> energy and momentum relaxation rates. <> We present a calculation of the lifetime and the elastic <> scattering rates for confined and interface modes in GaAs/AlAs <> quantum wells. It is found that the decay rates of the two <> modes exhibit different well-width dependences, and that <> scattering from interface roughness is the dominant mechanism <> for momentum relaxation. The implications for high-field <> transport are discussed. <> KP: SCATTERING <> <> (5) TI: ELECTRON-PHONON SCATTERING IN GA1-XALXAS QUANTUM-WELL <> STRUCTURES IN AN ELECTRIC-FIELD <> AU: ZHU_JL, DUAN_WH, GU_BL <> NA: TSING HUA UNIV,DEPT PHYS,BEIJING 100084,PEOPLES R CHINA <> CHINESE CTR ADV SCI & TECHNOL,WORLD LAB,CTR THEORET <> PHYS,BEIJING 100080,PEOPLES R CHINA <> CENT IRON & STEEL RES INST,BEIJING 100081,PEOPLES R CHINA <> JN: PHYSICAL REVIEW B-CONDENSED MATTER, 1994, Vol.50, No.8, <> pp.5473-5479 <> IS: 0163-1829 <> AB: Effects of the well width and an electric field on electron- <> phonon scattering are studied for two kinds of quantum-well <> structures. One is a symmetrical single quantum well (SSQW) <> Ga0.6Al0.4As/GaAs/Ga0.6Al0.4As, and the other is an <> asymmetrical single quantum well (ASQW) Ga0.6Al0.4As/GaAs- <> Ga0.8Al0.2As/Ga0.6Al0.4As. Calculated results reveal that for <> both structures without an electric field, the intrasubband and <> intersubband scattering rates due to interface phonons, <> respectively, decrease and increase with increasing well width <> while those due to confined phonons increase with increasing <> well width. It is found that the difference between SSQW and <> ASQW structures results in a significant change of phonon modes <> and electronic structure and consequently the dependence of <> scattering rates on an applied electric field is quite <> different for the two structures, and that the intersubband <> scattering rates can be considerably changed by applied <> electric field as the well width is large. The result would be <> useful for analyzing experimental results and designing some <> devices in the future. <> KP: PHOTOCURRENT SPECTROSCOPY, CONFINED LO, GAAS, EXCITONS, <> HETEROSTRUCTURES, POLARIZABILITY, SUPERLATTICES, VIBRATIONS, <> MODEL, RATES <> <> (6) TI: PHONON-SCATTERING SUPPRESSION IN SHORT PERIODIC ALAS/GAAS <> MULTIPLE-QUANTUM-WELL STRUCTURES <> AU: LETRAN_TT, SCHAFF_WJ, RIDLEY_BK, CHEN_YP, CLARK_A, EASTMAN_LF <> NA: CORNELL UNIV,SCH ELECT ENGN,PHILLIPS HALL,ITHACA,NY,14853 <> JN: JOURNAL OF APPLIED PHYSICS, 1994, Vol.75, No.7, pp.3491-3499 <> IS: 0021-8979 <> AB: The suppression of longitudinally polarized optical-phonon <> (LOP) electron scattering in multiple quantum wells (MQWs) was <> sought in short periodic AlAs/GaAs with well widths of 12, 15, <> and 20 monolayers and AlAs barrier widths of 2 and 4 <> monolayers, based on a study of electron mobility in the plane <> of the MQW. Two-dimensional electron-gas structures with MQWs <> of up to eight wells in their channel were grown. Their <> mobilities at room temperature were slightly reduced, as <> compared to samples without MQW channel, due to interaction <> with interface polaritons from AlAs barriers, while mobility at <> temperatures < 50 K improved due to reduction of remote ionized <> impurity scattering. The theoretical analysis of the results <> based on the model of hybridon-electron interaction in an <> infinite superlattice is presented. The reduction of room- <> temperature mobility in the MQWs is believed to be caused by <> the interaction of electrons with both barrier interface- <> polariton (IP) -like modes and the well LOP-IP hybrids. An <> alternative explanation of the results of a similar experiment <> done elsewhere is offered denying the evidence of strong <> suppression of LOP scattering there. <> KP: OPTICAL PHONONS, SUPERLATTICES, MOBILITY <> <> <> <> <> <> (12) TI: INTERACTION BETWEEN AN ELECTRON AND OPTICAL PHONONS IN POLAR <> SEMICONDUCTOR HETEROSTRUCTURES <> AU: SHI_JJ, PAN_SH, LIU_ZX <> NA: CHINA CTR ADV SCI & TECHNOL,WORLD LAB,POB 8730,BEIJING <> 100080,PEOPLES R CHINA <> HENAN NORMAL UNIV,DEPT PHYS,XINXIANG 453002,PEOPLES R CHINA <> CHINESE ACAD SCI,INST PHYS,BEIJING 100080,PEOPLES R CHINA <> JN: ZEITSCHRIFT FUR PHYSIK B-CONDENSED MATTER, 1996, Vol.100, No.3, <> pp.353-364 <> IS: 0722-3277 <> AB: Interface phonons and bulk-like longitudinal-optical (LO) <> phonons and their interaction with an electron are studied for <> a finite four-layer heterostructure (FFLHS). An analysis of the <> field eigenvectors shows that, in the vicinity of the <> Brillouin-zone center, an interface transverse-optical (TO) <> mode oscillates at the bulk LO frequency, and an interface LO <> mode oscillates at the bulk TO frequency. Analytic expressions <> and numerical illustrations for dispersion relations of <> interface modes and for electron-phonon coupling functions and <> scattering rates are obtained for finite, semi-infinite and <> infinite quantum well (QW) structures which are important <> special cases of an FFLHS. It is shown that the scattering <> rates depend strongly on the well width of a QW structure, and <> that interface modes are much more important than bulk LO modes <> when the well width is small. The calculated results also show <> that the usual selection rules for intersubband and <> intrasubband transitions break down in asymmetric <> heterostructures. Moreover, we have found an interesting <> result. That is, in comparison with the negligibly small <> interaction between an electron and the lowest-frequency <> interface-mode in symmetric single QWs and commonly used step <> QWs, this interaction may be very large in asymmetric single <> QWs and general step QWs. <> KP: QUANTUM-WELLS, COLLECTIVE EXCITATIONS, SCATTERING RATES, <> DIELECTRIC SLAB, LO PHONONS, INTERFACE, MODES, SUPERLATTICES, <> CRYSTALS, HETEROJUNCTIONS <> <> (13) TI: Electron capture in quantum wells via scattering by electrons, <> holes, and optical phonons <> AU: Kalna_K, Mosko_M <> NA: SLOVAK ACAD SCI,INST ELECT ENGN,DUBRAVSKA CESTA 9,SK-84239 <> BRATISLAVA,SLOVAKIA <> JN: PHYSICAL REVIEW B-CONDENSED MATTER, 1996, Vol.54, No.24, <> pp.17730-17737 <> IS: 0163-1829 <> AB: Electron-capture times due td the electron-electron (e-e), <> electron-hole (e-h), and electron-polar optical phonon (e-pop) <> interactions are calculated in the GaAs quantum well (QW) with <> electron and hole densities 10(11) cm(-2). The calculated <> capture times oscillate as a function of the QW width with the <> same period but with different amplitudes. The e-h capture time <> is two to four orders larger and the e-e capture time one to <> three orders larger than the e-pop capture time. The exceptions <> are the QW widths near resonance minima, where the e-e capture <> time is only 2-3 times larger and the e-h capture time 10-100 <> times larger. A different physical origin of the oscillatory <> behavior is demonstrated for the e-e and e-pop capture times. <> Effects of exchange and degeneracy on the e-e capture are <> analyzed. The exchange effect increases the e-e capture time <> approximately two times while the degeneracy does not change <> the capture time except for the QW depths and widths near the <> resonance. <> KP: CARRIER-CARRIER SCATTERING, MONTE-CARLO, GAAS, HETEROSTRUCTURES, <> THERMALIZATION, LASERS, PLASMA <> <> (14) TI: Electron scattering by optical phonons in AlxGa1- <> xAs/GaAs/AlxGa1-xAs quantum wells <> AU: Zianni_X, Simserides_CD, Triberis_GP <> NA: UNIV ATHENS,DEPT PHYS,SECT SOLID STATE PHYS,ZOGRAFOS <> 15784,ATHENS,GREECE <> JN: PHYSICAL REVIEW B-CONDENSED MATTER, 1997, Vol.55, No.24, <> pp.16324-16330 <> IS: 0163-1829 <> AB: The scattering of a quasi two-dimensional electron gas by <> optical phonons in selectively doped AlxGa1-xAs/GaAs/AlxGa1-xAs <> quantum wells is systematically studied in order to determine <> the effect of phonon confinement. The electron states are <> calculated solving self-consistently Schrodinger and Poisson <> equations to obtain an accurate dependence upon the structure <> parameters and the temperature. We study the way the scattering <> is affected by the form of the phonons calculating the mobility <> using three models for the phonons. They are considered: (a) as <> three dimensional (3D), (b) as a set of confined and interface <> phonons, and (c) as the normal modes of the heterostructure. <> The relaxation times for the electron energy subbands are <> calculated solving the system of Boltzmann equations. The <> effect of the temperature and the well width variation is also <> investigated. The results are in a good agreement with <> experimental measurements. The agreement is only slightly <> dependent on the model used for the phonons and becomes best <> when the effect of the heterostructure on the phonon modes is <> taken into account. <> KP: HETEROSTRUCTURES, MODULATION, MOBILITY <> <> (15) TI: Polar optical modes in semiconductor nanostructures <> AU: Velasco_VR, GarciaMoliner_F <> NA: CSIC,INST CIENCIA MAT,E-28049 MADRID,SPAIN <> UNIV JAUME I,CATEDRA CIENCIA CONTEMPORANEA,CASTELLO DE PLANA <> 12071,SPAIN <> JN: SURFACE SCIENCE REPORTS, 1997, Vol.28, No.5-6, pp.125-176 <> IS: 0167-5729 <> DT: Review <> AB: Polar optical modes play an important role in electron-phonon <> processes such as scattering rates, polaron effects and <> resonant Raman scattering in quantum wells and superlattices, <> Because of this there has been in recent years a strong <> interest in the development of a long-wave theory for optical <> modes in semiconductor nanostructures. This theory would be the <> equivalent of the effective mass theory for electrons. Besides <> microscopic calculations it should provide a satisfactory <> theoretical model to study the long-wave limit, to which most <> experimental evidence is circumscribed. Important elements in <> this type of theory are the inclusion of the bulk spatial <> dispersion of the optical modes together with the fact that, at <> an interface between two media, mechanical and electromagnetic <> boundary conditions must be satisfied, In some cases, like <> InAs/GaSb and related superlattices, the details of the <> interface structure are also important. We discuss here the <> different approaches employed to study the long-wave limit in <> these systems, including other approaches in which the envelope <> function model is derived directly from microscopic lattice <> dynamics. <> KP: ELECTRON-PHONON INTERACTION, GAAS-ALAS SUPERLATTICES, ENERGY- <> LOSS SPECTRUM, PLANAR VIBRATIONAL-MODES, RECTANGULAR QUANTUM <> WIRE, RAMAN-SCATTERING, GAAS/ALAS SUPERLATTICES, CONFINED LO, <> INTERFACE MODES, RESONANT RAMAN <> WA: phonons, heterostructures, quantum wells, superlattices <> <> <> <> **** End of Data **** <> <> <> ----- End Included Message ----- <>
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