We have studied the electronic properties of delta-doped In 0.22 Ga 0.78 As/ GaAs quantum wells ͑QWs͒ by van der Pauw Hall measurements and Shubnikov-de Haas measurements. From the temperature-dependent van der Pauw Hall measurements, we observed two kinds of donors, which have binding energies of 104± 7 and 9.6± 0.1 meV. After inserting In 0.1 Ga 0.9 As layers between the In 0.22 Ga 0.78 As and GaAs layers, a single donor with binding energy of 50± 2 meV was observed. The carrier concentration determined by SdH measurements did not change after the QWs were illuminated at low temperature, which indicates that these deep donors could not produce a persistent photoconductivity in delta-doped In 0.22 Ga 0.78 As/ GaAs QWs.