Magnetic depopulation of sub-bands in In0.53Ga0.47As/In0.52Al0.48As heterojunctions

Newson, D.J.; Berggren, Karl‐Fredrik; Pepper, M.; Myron, H.W.; Davies, Graham; Scott, E.G.

doi:10.1088/0022-3719/19/19/003

Cited by 18 publications

(3 citation statements)

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“…6.12 from which the empirical law: is deduced, with nj in cm"2. This carrier concentration dependence is in reasonable agreement with Harris et al who find an exponent of 2/3, but not with the variational calculations (Ando 1982, Walukiewicz et al 1984, Newson et al 1986) which find the extent of the wavefunction scaling like n"1/3 (cf. Eqn.…”

Section: 41___enhancement Of the G-factorsupporting

confidence: 87%

“…6.11, also Razeghi el al. 1986), GalnAs-AlInAs (Portal et al 1982, Newson et al 1986 and HgCdTe (Singleton et al 1986) where a significant increase in resistivity is seen just before depopulation. A magnetic field in the plane of the 2DEG has the effect of compressing the electronic wavefunction closer to the interface, making interface roughness scattering more important at higher fields.…”

Section: 41___enhancement Of the G-factormentioning

confidence: 99%

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Electron-Phonon Interactions in Low-Dimensional Structures

Challis¹

2003

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Transport properties of the two-dimensional electron gas (2DEG) in high magnetic fields are used to investigate scattering processes affecting the resistivity of GaAs-GaAlAs and GalnAs-InP heterojunctions and quantum wells: especially coupling of electrons to acoustic and optic phonons; and transitions between electric subbands. The experiments fall into two groups:A systematic study of magnetophonon resonance (MPR) between 30K and 300K.Resonance positions indicate a coupling substantially below the LO phonon energy, expected from 3D measurements. GaAs-GaAlAs hetero junctions show amplitudes varying smoothly with electron density (n,) and closely related to the 4K mobility. On rotation in magnetic field they decrease rapidly as the resonance position returns to the LO value.In modulation doped structures the damping factor is determined by remote impurity scattering. As ns is increased in GalnAs-InP the coupling frequency decreases dramatically from the GaAs-like LO at 272cm'1 to the InAs-like TO at 226cm'1. At higher electric fields the 'normal 1 MPR maxima invert, starting at low magnetic fields, to form 'hot electron' MPR minima, with maximum amplitude at ~60K. This is the first direct observation of HEMPR in 2D and is explained in a diffusion picture. At lower electric fields, additional resonances are identified with resonant cooling by inter-subband scattering. Comparisons are made with calculations and explanations sought including consideration of interface phonons; coupled plasmon-phonon modes; and shifts of the resonance positions due to the shape of the density of states. Low temperature magnetoresistance measurements in GaAs-GaAlAs heterojunctions with more than one occupied electric subband. Shubnikov-de Haas oscillations in perpendicular magnetic fields contain non-additive terms at electron temperatures ^ 2K, where acoustic phonon mediated inter-subband scattering is comparable to intra-subband scattering. Subband separations and greatly enhanced g-factors [largest for electrons in the upper subband ] are deduced from the oscillations. Damping of the oscillations in field, gives values for quantum lifetimes (T,), much smaller than r t, deduced from mobility. With two subbands occupied T S is always largest for the upper subband, while relative sizes of r i depend on sample quality. Study of electron energy loss rates, from thermal damping of the oscillations, shows enhancement in the region kT e ~ fiu>c, which is evidence for cyclotron phonon emission. Depopulating subbands in parallel fields causes the resistance to drop, by up to 60%, due to suppression of inter-subband scattering. Systematic studies show this scattering rate is independent of ns.I wish to express my gratitude to all those who have made the work of this thesis both possible and enjoyable. I would especially like to thank:-

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Section: 41___enhancement Of the G-factorsupporting

confidence: 87%

Section: 41___enhancement Of the G-factormentioning

confidence: 99%

Electron-Phonon Interactions in Low-Dimensional Structures

Challis¹

2003

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“…This was treated theoretically by Stern [l71 and first reported in InAs by Doezema et a1 [18]. This effect has been observed in GaAs-Ga,_,Al,As [19], Ga,-,In,As-InP [20] and Ga,_,In,As-Al,-,In,As heterojunctions [21,22] and Hg,_,Cd,Te-anodic oxide systems [23] for example.…”

Section: The Diamagnetic Shubnikov-de Haas Effectmentioning

confidence: 91%

Shubnikov-de Haas effect of the quasi-two-dimensional electron system in InSb grain boundaries in tilted magnetic fields

Nachtwei¹,

Bassom²,

Nicholas³

et al. 1989

Semicond. Sci. Technol.

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The Shubnikov-de Haas effect and the Hall effect of a quasi-twodimensional inversion layer adjacent to the grain boundary in an lnSb bicrystal are investigated in magnetic fields up to 9 T at various angles from 0" to 90" between the grain boundary plane normal vector and the field direction at a temperature of 1.5 K. Whereas the Hall effect and the oscillations of the magnetoresistance of the ground electric subband are due to t h e perpendicular magnetic field component only, the SDH oscillations of the first excited subband show remarkable deviations from the ideal two-dimensional behaviour. The experimental results yield a non-vanishing dispersion relation perpendicular to the interface, which is shown to be possibly due to the spatial extension of the wavefunction of the first subband. Observations of the diamagnetic Shubnikov-de Haas effect show good agreement with theoretical predictions and confirm calculations indicating that four subbands are occupied in the system.

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Properties of a high‐mobility two‐dimensional electron gas in modulation‐doped quantum well structures of GaInAs/AIInAs and GaInAs/(Ga_1−xAl_x)InAs heterostructures

Kraak

Oelze

Künzel

et al. 1994

Physica Status Solidi (b)

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The electronic and magnetotransport properties of the two-dimensional electron gas (2DEG) in MBE-grown GaInAs/AlInAs and GaInAs/(Ga, -,Al,)InAs heterostructures are investigated in magnetic fields up to 12 T. The quantum oscillations of the magnetoresistivity (SdH effect) and the observation of pronounced quantum Hall effect demonstrate the existence of a high-mobility 2DEG in the GaInAs potential well. The characteristic parameters of the electronic band structure of the 2DEG are determined and are compared with self-consistent solutions of the coupled Poisson and Schrodinger equations. The influence of hydrostatic pressure on the magnetotransport properties is studied. A surprisingly weak change of the subband occupation with pressure is revealed.Die elektronischen und die Magnetotransport-Eigenschaften des zweidimensionalen Elektronengases (2DEG) in MBE-gewachsenen GaInAs/AlInAs-und GaInAs/(Ga, -.Al,)InAs-Heterostrukturen werden in Magnetfeldern bis zu 12 T untersucht. Die Quanta-Oszillationen des Magnetowiderstandes (SdH-Effect) und die Beobachtung eines deutlich ausgepragten Quanten-Halleffektes beweisen klar die Existenz eines 2DEG rnit hoher Beweglichkeit in der GaInAs-Grenzflachenschicht. Die charakteristischen Parameter der elektronischen Bandstruktur des 2DEG werden experimentell bestimmt und mit den Ergebnissen einer selbstkonsistenten Berechnung der gekoppelten Poisson-und SchrodingerGleichung verglichen. Es wird der EinfluB des hydrostatischen Druckes auf die MagnetotransportEigenschaften untersucht, wobei nur eine iiberraschend geringe Veranderung der Subband-Besetzung unter Druck festzustellen ist.

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Magnetic depopulation of sub-bands in In_0.53Ga_0.47As/In_0.52Al_0.48As heterojunctions

Cited by 18 publications

References 8 publications

Electron-Phonon Interactions in Low-Dimensional Structures

Electron-Phonon Interactions in Low-Dimensional Structures

Shubnikov-de Haas effect of the quasi-two-dimensional electron system in InSb grain boundaries in tilted magnetic fields

Properties of a high‐mobility two‐dimensional electron gas in modulation‐doped quantum well structures of GaInAs/AIInAs and GaInAs/(Ga_1−xAl_x)InAs heterostructures

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Magnetic depopulation of sub-bands in In0.53Ga0.47As/In0.52Al0.48As heterojunctions

Cited by 18 publications

References 8 publications

Electron-Phonon Interactions in Low-Dimensional Structures

Electron-Phonon Interactions in Low-Dimensional Structures

Shubnikov-de Haas effect of the quasi-two-dimensional electron system in InSb grain boundaries in tilted magnetic fields

Properties of a high‐mobility two‐dimensional electron gas in modulation‐doped quantum well structures of GaInAs/AIInAs and GaInAs/(Ga1−xAlx)InAs heterostructures

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Magnetic depopulation of sub-bands in In_0.53Ga_0.47As/In_0.52Al_0.48As heterojunctions

Properties of a high‐mobility two‐dimensional electron gas in modulation‐doped quantum well structures of GaInAs/AIInAs and GaInAs/(Ga_1−xAl_x)InAs heterostructures