Coexistence of Wannier-Stark transitions and miniband Franz-Keldysh oscillations in strongly coupled GaAs-AlAs superlattices

Schmidt, Klaus; Linder, N.; Döhler, G. H.; Grahn, H. T.; Ploog, K.; Schneider, Harald

doi:10.1103/physrevlett.72.2769

Cited by 39 publications

(17 citation statements)

References 12 publications

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“…More recent studies refer to the transition between the Franz-Keldysh oscillations and the WannierStark ladder [26], and the influence of higher valleys in the band structure [27].…”

Section: Experimental Summarymentioning

confidence: 99%

Semiconductor superlattices: a model system for nonlinear transport

2002

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Electric transport in semiconductor superlattices is dominated by pronounced negative differential conductivity. In this report the standard transport theories for superlattices, i.e. miniband conduction, Wannier-Stark-hopping, and sequential tunneling, are reviewed in detail. Their relation to each other is clarified by a comparison with a quantum transport model based on nonequilibrium Green functions. It is demonstrated how the occurrence of negative differential conductivity causes inhomogeneous electric field distributions, yielding either a characteristic sawtooth shape of the current-voltage characteristic or self-sustained current oscillations. An additional ac-voltage in the THz range is included in the theory as well. The results display absolute negative conductance, photon-assisted tunneling, the possibility of gain, and a negative tunneling capacitance. 2 Notation and list of symbolsThroughout this work we consider a superlattice, which is grown in the z direction. Vectors within the (x, y) plane parallel to the interfaces are denoted by bold face letters k, r, while vectors in 3 dimensional space are r, k, . . . . All sums and integrals extend from −∞ to ∞ if not stated otherwise.The following relations are frequently used in this work and are given here for easy reference:

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“…More recent studies refer to the transition between the Franz-Keldysh oscillations and the WannierStark ladder [26], and the influence of higher valleys in the band structure [27].…”

Section: Experimental Summarymentioning

confidence: 99%

Semiconductor superlattices: a model system for nonlinear transport

2002

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“…In Fig. 2, fine oscillation structures appear in the electric-fieldstrength region below 20 kV/cm, which results from FranzKeldysh (FK) oscillations related to the miniband structures [13]. With an increase in electric field strength, the FK oscillation disappears, which originates from the localization of the envelope functions, then the ER signal related to the interband transition, which is labeled H11(0), between the E1(0) state and the n = 1 heavy-hole [HH(0)] state appears at ~1.568 eV.…”

Section: Resultsmentioning

confidence: 97%

Bistability operation of photocurrent due to wave‐function coupling of Wannier‐Stark localization states in a GaAs/AlAs superlattice

Hasegawa

Nakayama

2008

Phys. Status Solidi (c)

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We have investigated effects of the resonant wave‐function coupling between Wannier‐Stark localization states on photocurrent properties in a GaAs (6.8 nm)/Al0.1Ga0.9As (4.0 nm) superlattice. The resonant coupling, which causes an anticrossing behavior of the relevant transition energies, were clearly detected by electroreflectance spectroscopy and analyzed by calculating the Wannier‐Stark localization states as a function of electric field strength. It is found that the photocurrent‐voltage characteristics exhibit a peak structure, which results in a negative differential resistance, owing to a change of the optical transition probability under the resonant‐coupling condition between the first and second quantized electron states in adjacent quantum wells. Utilizing this negative differential resistance property, we have demonstrated a photocurrent‐bistability operation of a self‐electro‐optic effect device. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Recently, Schmidt et al [9] and Linder et al [10] reported the FK oscillations at the miniband edge in a GaAs/AlAs SL with a very wide miniband (∼330 meV for the first electron miniband) by using differential photocurrent (PC) spectroscopy. They suggested the coexistence of the FK oscillations and the WS localization.…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, we have investigated the FK oscillations at the miniband edge in a GaAs/Al 0.1 Ga 0.9 As SL embedded in a p-i-n structure by using electroreflectance (ER) spectroscopy which is a major method used to observe the FK oscillations in bulk semiconductors. The width of the first electron miniband is estimated to be 27 meV which is much narrower than that of the sample used in [9,10]. The profiles of the FK oscillations remarkably depend on the electric field: the oscillation direction changes from the low-energy side to the high-energy side with the increase of the electric field, then the FK oscillations disappear in the high-field regime of the WS localization.…”

Section: Introductionmentioning

confidence: 99%