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HL: Halbleiterphysik
HL 4: Ultrakurzzeitph
änomene
HL 4.10: Vortrag
Montag, 8. März 2004, 12:30–12:45, H13
THz photomixer based on quasi-ballistic transport in AlGaAs nipnip-superlattices — •Frank H. Renner1, O. Klar1, S. Malzer1, M. Eckardt1, A. Schwanhäußer1, G. Loata2, T. Löffler2, H. Roskos2, D. Driscoll3, M. Hanson3, A.C. Gossard3, and G.H. Döhler1 — 1Insitut für Technische Physik I, Universität Erlangen-Nürnberg , Germany — 2Lehrstuhl für Ultrakurzzeitphysik, Universität Frankfurt a.M., Germany — 3Materials Departement, UC Santa Barbara, U.S.A.
Conventional THz-photomixers are antenna-structures on a LT-GaAs-layer and are based on the photoconductivity of LT-GaAs, characterized by an extremely short carrier-lifetime . We have developed a novel concept for photomixing based on the quasi-ballisitic transport of electrons in AlGaAs-i-layers. In this concept, the emitter is not limited by the lifetime of the photogenerated carriers and its efficiency proves to be higher than in conventional LT-photomixers.
The emitter consists of a stack of nano-pin-diodes. The lengths and Al-contents of the i-layers in this nipnip-superlattice are optimized for the transport of the carriers. Recombination of the photogenerated carriers takes place inside the recombination-enhanced np-diodes between the nano-pin-diodes. The THz-modulated current is fed into an attached planar antenna, which is either a resonant dipole-antenna or a non-resonant spiral- or log. periodic-antenna.
In this contribution we present the concept of the nipnip-emitter and its realization in the AlGaAs material system, including experimental results on the THz-output and frequency response of the emitter.