Electronic and optical properties of modulation doped semiconductor quantum wells

Abstract

We report on calculations of electronic and optical properties of modulation doped quantum well heterostructures based on a multiband effective mass approach which incorporates mixing of heavy and light hole states. The modulation doped quantum well structure is of special interest, because its electronic and optical properties can be substantially modified by adjusting the bias voltage across the sample. The valence sub-band structure is found to be a complicated function of the width and depth of the well and the doping potential; hence the zone center effective hole masses depend nontrivially on these parameters. Our calculations show that for some values of the well parameters the second valence subband has a negative effective mass. By choosing this effective hole mass to be equal to the negative of the effective electron mass a singularity can be created in the joint density of states causing sharp peaks to appear in the absorption and photoconductivity spectra.