Magnetoluminescence and Raman study of GaAs/AlAs multiple quantum well structure doped n-type in the AlAs barrier layers

摘要

We present a photoluminescence and Raman study of a GaAs/AlAs multiple quantum well structure doped n-type in the AlAs barriers. Electrons transfer from the silicon donor states associated with the AlAs X-valley minima to the GaAs wells where they form a dense quasi two-dimensional electron gas. At zero magnetic field the luminescence spectrum is broad and featureless lacking any sharp excitonic features characteristic of undoped wells. In the presence of a magnetic field applied parallel to the growth axis the luminescence exhibits a number of distinct lines that are due to interband transitions between conduction and valence band Landau levels. The Raman spectra were excited in resonance with the e$-3$/h$-3$/ exciton. At zero field a feature associated with the e$-1$/ $YLD e$-2$/ intersubband transition is observed. When an external magnetic field is applied, this feature evolves into a combination mode between the e$-1$/ $YLD e$-2$/ transition and the electron cyclotron resonance.