Deep levels in GaAs due to Si δ doping

delta (Si)-doped GaAs samples grown by metalorganic vapor phase epitaxy are studied by capacitance-voltage and deep level transient spectroscopy (DLTS) techniques. A detailed analysis of the DLTS signal (including spatial profiles) is performed. DLTS spectra exhibit a clear development depending on the sheet dopant concentration ranging from 5 x 10(14) to 2 x 10(16) m(-2). Two observed peaks do not change its activation energy with the doping level while their amplitude increases rapidly when the doping rises. We assign them to defects generated by high silicon concentration, probably related to gallium vacancy. Another peak in the most densely doped sample seems to correspond to the DX level which is occupied near the Slayer. Peculiar features of the EL2 level are observed in delta -doped GaAs and explained by the band bending due to the dopant sheet. No indication of the emission from the quantum confinement states is found in DLTS spectra taken at temperatures 80-400 K. (C) 2000 American Institute of Physics. [S0021-8979(00)05524-9].