Microwave-modulated photoluminescence of a two-dimensional electron gas
10 April 2007
The primary effect of microwave (mw) irradiation on a two dimensional electron gas (2DEG) is heating due to mw absorption by the electrons. At low lattice temperatures, pronounced secondary effects are observed: mw-induced modification of the photoluminescence (PL) spectrum and mw-induced resistance oscillations (MIRO). We present an experimental study of mw-modulated PL (MPL) spectroscopy in modulation-doped GaAs/AlGaAs QW's. At low magnetic field strengths (B 0.5 T and intense mw-irradiation, new optically detected resonances (ODRs) are observed at magnetic fields that depend on the 2DEG density and approximately correspond to integer electron filling factors. We argue that these resonances result from a slight 2DEG density increase under mw irradiation with a concurent, low-energy PL spectral shift due to a small bandgap, narrowing.