Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 3: Halbleiterlaser I

HL 3.3: Vortrag

Montag, 24. März 2003, 11:00–11:15, BEY/81

Short-wavelength intersubband transitions in InGaAs/AlAs quantum well — •N. Georgiev¹, M. Semtsiv², T. Dekorsy¹, F. Eichhorn¹, A. Bauer¹, M. Helm¹, and W.T. Masselink² — ¹Institute of Ion Beam Physics and Materials Research, Forschungszentrum Rossendorf, P.O.Box 510119, D-01314 Dresden, Germany — ²Humboldt-University Berlin, Department of Physics, Invalidenstrasse 110, D-10115, Berlin, Germany

InGaAs/AlAs quantum wells (QWs) have the potential for the development of new devices based on intersubband transitions, such as near-infrared detectors, ultra-fast switches and light emitters that operate at the communication wavelength of 1.55 µm. However, the increased strain accommodation in the InGaAs/AlAs system considerably affects the band offsets of these QW structures and the performance of the appropriate devices. We report structural and optical characterization of In_xGa_1−xAs/AlAs/ In_yAl_1−yAs (x∼0.7, y∼0.55) QW structures grown on InP substrates. In these structures, we utilize the high conduction band offset provided by AlAs. An increased In content in the wells and in the In_yAl_1−yAs layers helps to compensate the large AlAs tensile strain. Additionally, the smaller InGaAs band gap results in a shift of the first Γ-like well subband to lower energies relative to the X-minimum in the barrier layers even in very narrow wells. Intersubband absorption at wavelengths shorter than 2.0 µm is observed in thin single QWs. Also presented are spectra of asymmetric coupled QWs and short-period superlattices.