EXCITONS IN TYPE-II QUANTUM-DOT SYSTEMS - A COMPARISON OF THE GAAS/ALAS AND INAS/GASB SYSTEMS

被引:34
作者
RORISON, JM
机构
[1] Sharp Laboratories of Europe Ltd., Oxford OX4 4GA, Edmund Halley Rd., Oxford Sci. Pk.
来源
PHYSICAL REVIEW B | 1993年 / 48卷 / 07期
关键词
D O I
10.1103/PhysRevB.48.4643
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
A calculation of the exciton binding energy (E(x)) and oscillator strength for quantum dots in type-II semiconductor systems is presented. These structures consist of a spherical dot of one semiconductor embedded in a second semiconductor. As in the type-II exciton systems in quantum wells the electron is confined in one semiconductor and the hole is confined in the other due to band lineups in the two materials which make this arrangement energetically favorable. We have considered the systems (i) GaAs/AlAs where the electron is confined in the X state in the AlAs while the hole is confined in the GaAs dot (for a dot radius of less than 56 angstrom) and (ii) InAs/GaSb where the electron is confined in the InAs dot while the hole is confined in the GaSb (for a dot of radius less than 87 angstrom). While both of these systems are indirect in real space the GaAs/A]As system is also indirect in k space. We compare E(x) in the type-II dot to E(r), the binding energy of a bulk hydrogenic impurity in the bulk barrier. We find that for the case of infinite barriers E(x) < E(r). For the finite barrier case with wave-function leakage into the dot, E(x) much greater than E(r) due to the effect of the overlapping electron and hole wave functions within the dot. The values of E(x) for a type-II dot system are vastly larger than those for a type-II quantum-well system due to the extra correlation in the other two confined dimensions and for the GaAs/AlAs system the values are comparable to the type-I E(x) values for 30 < a < 70 angstrom where a, is the radius of the dot.
引用
收藏
页码:4643 / 4649
页数:7
相关论文
共 24 条
  • [11] EFROS AL, 1982, SOV PHYS SEMICOND+, V16, P772
  • [12] THEORY OF OPTICALLY-EXCITED INTRINSIC SEMICONDUCTOR QUANTUM DOTS
    HU, YZ
    LINDBERG, M
    KOCH, SW
    [J]. PHYSICAL REVIEW B, 1990, 42 (03): : 1713 - 1723
  • [13] EXCITONS IN CUCL MICROCRYSTALS EMBEDDED IN NACL
    ITOH, T
    KIRIHARA, T
    [J]. JOURNAL OF LUMINESCENCE, 1984, 31-2 (DEC) : 120 - 122
  • [14] QUANTUM-SIZE EFFECTS OF INTERACTING ELECTRONS AND HOLES IN SEMICONDUCTOR MICROCRYSTALS WITH SPHERICAL SHAPE
    KAYANUMA, Y
    [J]. PHYSICAL REVIEW B, 1988, 38 (14): : 9797 - 9805
  • [15] WANNIER EXCITONS IN LOW-DIMENSIONAL MICROSTRUCTURES - SHAPE DEPENDENCE OF THE QUANTUM SIZE EFFECT
    KAYANUMA, Y
    [J]. PHYSICAL REVIEW B, 1991, 44 (23): : 13085 - 13088
  • [16] MADELUNG O, 1982, LANDOLTBORNSTEIN, V17
  • [17] ENERGY-SPECTRA OF DONORS IN GAAS-GA1-XALXAS QUANTUM WELL STRUCTURES IN THE EFFECTIVE-MASS APPROXIMATION
    MAILHIOT, C
    CHANG, YC
    MCGILL, TC
    [J]. PHYSICAL REVIEW B, 1982, 26 (08): : 4449 - 4457
  • [18] SEMICONDUCTOR QUANTUM-WIRE STRUCTURES DIRECTLY GROWN ON HIGH-INDEX SURFACES
    NOTZEL, R
    LEDENTSOV, NN
    DAWERITZ, L
    PLOOG, K
    HOHENSTEIN, M
    [J]. PHYSICAL REVIEW B, 1992, 45 (07): : 3507 - 3515
  • [19] PULSFORD N, 1990, THESIS OXFORD U
  • [20] SPATIAL QUANTIZATION IN GAAS-ALGAAS MULTIPLE QUANTUM DOTS
    REED, MA
    BATE, RT
    BRADSHAW, K
    DUNCAN, WM
    FRENSLEY, WR
    LEE, JW
    SHIH, HD
    [J]. JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, 1986, 4 (01): : 358 - 360