Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Halbleiterphysik

HL 14: Poster I

HL 14.63: Poster

Montag, 24. März 2003, 17:00–19:30, HSZ/P2

Time-resolved far-infrared laser spectroscopy of quantum Hall systems — •C. Stellmach¹, A. Hirsch¹, N. G. Kalugin¹, H.-W. Hübers², S. G. Pavlov², B. E. Sagol¹, G. Hein³, and G. Nachtwei¹ — ¹Inst. f. Techn. Phys., TU-Braunschweig, Menselssohnstr. 2, D-38106 Braunschweig — ²Deutsches Zentrum f. Luft- u. Raumfahrt, D-12489 Berlin — ³Phys.-Techn. Bundesanstalt, Bundesallee 100, D-38116 Braunschweig

We present measurements of the far-infrared (FIR) photoconductivity of quantum Hall systems, which are promising for high sensitive and tunable FIR detectors. In our time-resolved measurements we see different contributions. A longer response (hundreds of µs to some ms) corresponds to the change of the longitudinal resistance R_xx and a faster (some µs) response corresponds to the change of the longitudinal resistance R_xy. We also discuss the tuning of spectral response region by the electric field of a gate electrode.

The probe FIR source was a p-Ge cyclotron resonance laser, which is tunable by magnetic field in the wavelength range 120-160µm, and provides laser pulses of about 0.5µs duration (with 1W peak power, 1Hz repetition rate). For reaching a higher time resolution, we realised an electrical pumping pulse source (V_max = 4kV, I_max of about 200A) with controllable pulse width (from 300ns to few µs) and very sharp switching (dV/dt ≈ 150 V/ns). The source allowed us to evaluate the lower limit of pulse duration necessary to generate lasing (about 100ns).