Experimental Determination of the Subband Electron Effective Mass in InGaAs/InAlAs HEMT-structures by the Shubnikov – de Haas Effect at Two Temperatures

The electron effective masses m* in different dimensionally quantized subbands in InGaAs/InAlAs HEMT-structures have been measured by the Shubnikov – de Haas effect at two temperatures whose ratio was not equal to 2. The electron effective masses were found separately for the every subband. It was realized by digital bandpass filtering of the Shubnikov – de Haas oscillation to monochromatic oscillations corresponding to subbands. We obtained the dependence of m* in every subband on InAs content in quantum well.