LUMINESCENCE AND PHOTOMODULATED TRANSMISSION MEASUREMENTS IN INGAAS GAAS MODULATION-DOPED SINGLE QUANTUM-WELLS/

Photoluminescence and photomodulated transmission measurements on In0. 2Ga0.8As/GaAs/Al0.3Ga0.7As modulation doped pseudomorphic single quant um wells are presented. Photomodulated transmission spectra at low tem peratures showed sharp lines that are separated with respect to the lu minescence peaks due to the Stokes shift. From the Stokes shift we est imated the Fermi energy and the two-dimensional electron gas density. The obtained results are in good agreement with Shubnikov-de-Haas data . The temperature dependence of the optical spectra was also investiga ted. The photomodulated transmission technique is shown to be a good t ool to evaluate the electronic properties of modulation doped single q uantum well structures, including an estimation of the Fermi energy an d the two-dimensional electron gas density.