Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 9: Heterostrukturen I

HL 9.2: Talk

Monday, March 8, 2004, 15:30–15:45, H17

Time-domain THz spectroscopy of electronic exitations in GaAs/AlGaAs superlattices — •André Dreyhaupt, Stephan Winnerl, Thomas Dekorsy, and Manfred Helm — Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Rossendorf, Postfach 51 01 19, 01314 Dresden

We investigate the electronic properties of weakly and more strongly coupled n-doped GaAs/AlGaAs superlattices by time-domain THz spectroscopy in the low frequency range from about 0.5 to 3.5 THz. The sample properties are modulated either by applying an AC voltage via a gate electrode or by injecting a vertical current. The transmission signal is detected at the frequency of the modulation voltage with a lock-in amplifier leading to a signal-to-noise ratio superior compared to conventional FTIR spectroscopy in this frequency range. We will discuss the observation of inter-miniband transitions, confined donor transitions, plasmon excitations and the measurement of intra-miniband THz conductivity in a wide range of lattice temperatures.