Junction spectroscopy of highly doped GaAs: detection of the EL2 trap

The disappearance of the electron trap at E_t=E_c-0.82 eV (EL2) level in highly doped samples, observed in the literature for N_D-N_A>1x10^17 cm^(-3) has been assessed by junction spectroscopy investigations of liquid-encapsulated Czochralski GaAs:Te with N_D-N_A up to about 7x10^17 cm^(-3). By choosing appropriate spectroscopy methods, we have detected the EL2 peak, even in the most doped sample. This shows that such a defect is present in the material, but its detection is controlled by the quasi-Fermi level position in the gap, which also affects the Schottky diode operating conditions