Intersubband transitions in partially interdiffused GaAs/AlGaAs multiple quantum-well structures

• Published in: Journal of applied physics 1991-08, Vol.70 (4), p.2195-2199
• Main Authors: RALSTON, J. D, RAMSTEINER, M, DISCHLER, B, MAIER, M, BRANDT, G, KOIDL, P, AS, D. J
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.350334

Continuous tuning over the entire 8–12 μm wavelength range is demonstrated for the intersubband absorption resonance in n-doped GaAs/AlxGa1−xAs multiple quantum-well structures following partial interdiffusion of the well and barrier layers via rapid thermal annealing. The data indicate that redshifting of the intersubband absorption resonance arises both from interdiffusion-induced modification of the confining potential and from a decrease in the depolarization shift. The latter effect is due in part to a decrease in the free-carrier concentration within the Si-doped quantum wells following rapid thermal annealing. Significant diffusion of the localized Si dopant is also observed over the range of annealing temperatures investigated here. Calculated values of the Al-Ga interdiffusion coefficient, as a function of anneal temperature, indicate that Si diffusion through the heterointerfaces contributes substantially to layer intermixing.