Electric-field domain formation in type-II superlattices

Abstract

Static electric-field domains as well as current self-oscillations due to domain-wall oscillations have been observed in undoped, type-II GaAs-AlAs superlattices under photoexcitation. Photoluminescence measurements clearly demonstrate the coexistence of low-and high-field domains in the static and oscillating domain voltage regime. A comparison with the calculated energy level distribution indicates that the static domains are connected with negative differential velocity ͑NDV͒ due to resonant transfer between X 2 in the AlAs layer and ⌫ 1 in the GaAs layer, while the oscillating domains are attributed to NDV originating from resonant tunneling between X 1 and X 2 in the AlAs layers. This observation demonstrates the importance of transport channels due to the indirect band structure of type-II superlattices. ͓S0163-1829͑96͒51328-7͔

Anomaly of the current self-oscillation frequency in the sequential tunneling of a doped GaAs/AlAs superlattice

“…Under the right conditions, such structures have current-voltage characteristics with regions of negative differential resistance ͑NDR͒, leading to a range of important possible applications. Many interesting phenomena related to the NDR have been found in superlattices ͑SLs͒, ranging from a sawtoothlike branch of the current-voltage characteristic on the sequential resonance tunneling plateau, [5][6][7][8][9][10] current self-oscillations, [11][12][13] and chaos.…”

“…[10][11][12] The oscillation can be induced by continuous illumination of a laser light 13 or by a change of doping. 11 Recently, it has been shown that this selfoscillation can also be induced by applying an external magnetic field parallel to the SL layers or by varying temperature.…”

General analysis of instabilities and oscillations of the sequential tunneling in superlattices

“…14 Self-oscillation has been observed in both doped and undoped SL systems. [10][11][12] The oscillation can be induced by continuous illumination of a laser light 13 or by change of doping. 11 Recently, it has been shown that this self-oscillation can also be induced by applying an external magnetic field parallel to the SL layers.…”

“…Under the right conditions, such structures have current-voltage characteristics with regions of negative differential resistance ͑NDR͒, leading to a range of important possible applications. Many interesting phenomena related to the NDR have been found in superlattices ͑SL͒, ranging from current-voltage oscillations on the sequential resonance tunneling plateau, [5][6][7][8][9][10] current self-oscillations, [11][12][13] and chaos. 14 Self-oscillation has been observed in both doped and undoped SL systems.…”

Photocurrent self-oscillations in a spatially direct GaAs/AlGaAs superlattice

“…[6][7][8] In these studies the X states of the AlAs barriers were important in engineering long recombination times. Previous observations of photocurrent selfoscillations have been restricted to the GaAs-AlAs material system.…”