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Electric-field effects on above-barrier states in GaAs/Al(x)Ga(1-x)As superlattice

Elektrische Feldstärke-Effekte auf Zustände oberhalb der Barrieren in einem GaAs/Al(x)Ga(1-x)As Übergitter


Physical Review. B 51 (1995), No.7, pp.4236-4241
ISSN: 0163-1829
ISSN: 1098-0121
ISSN: 0556-2805
Journal Article
Fraunhofer IAF ()
Halbleiter; semiconductor; superlattice; Übergitter; Wannier-Stark localization; Wannier-Stark-Lokalisierung

We have investigated electric-field effects on the above-barrier states in a GaAs (7.0 nm)/Al sub0.1 Ga sub0.9 As (3.5 nm) superlattice clad by p-type and n-type Al sub0.3 Ga sub0.7 As layers using electroreflectance spectroscopy for detecting the interband optical transitions and using a transfer-matrix method for calculating the eigenenergies. It is demonstrated that the electric-field dependence of the energies of the optical transitions associated with the above-barrier states exhibits a similar feature of the Stark-ladder states below the barrier potential. In addition, it is found from the line-shape change of the electroreflectance signals that the above-barrier state resonantly couples with the spatially separated below-barrier state. The lineshape change results from the formation of bonding and antibonding states and wave-function delocalization over the coupling space. The transfer-matrix analysis explains the above experimental results reasonably well.