Microwave-modulated reflectance spectroscopy in a GaAs/AlGaAs heterostructure
GaAs/AlGaAs异质结的微波调制反射谱

A microwave-modulated reflectance spectroscopy (MMRS) measurement system was constructed and this MMRS technique was used to identify a transition from holes in valence band to electrons in the ground subband (GS) of the two-dimensional electron system (2DES) embedded in a GaAs/AlGaAs heterostructure sample. The temperature (T) dependence of the MMRS shows a blue shift of the energy gap with increasing T, while the magnetic field (B) dependence of the MMRS shows a red shift of the energy gap with increasing B: both phenomena are attributed to the bandfilling effect of holes in valence band in the GaAs/AlGaAs heterostructure. A theoretical simulation based on Kramers-Kronig relation was also presented which was comparable with the experimental data.