Characterization of semi-insulating GaAs:Cr by means of DC-CPM technique

Abstract- In the present paper, constant photocurrent method, ‘CPM ’ is used to determine the defects distribution from the optical absorption spectra of semi-insulating Cr-doped GaAs. By using the derivative method, we have extracted the distribution of the density of states DOS close to valence band edge Ev from the measured optical absorption spectrum. We have also developed a computer code program dc-CPM which have been used to compute the total absorption spectrum and their components using a model density of states inferred from two complementary techniques: constant photocurrent method, ‘CPM ’ and transient photocurrent ‘TPC’. It is found that by combination of the two measurement techniques ‘CPM ’ and ‘TPC’, and the two absorption spectra components αn and αp, we are able to have a full reconstruction of the density of states distribution below and above the Fermi level for such materials. Résumé- Dans ce présent travail, on a déterminé la distribution énergétique des défauts du GaAs:Cr en utilisant son spectre d’absorption optique mesuré par la technique du photo courant constant, ‘CPM’. Ainsi et par dérivation du spectre d’absorption optique mesuré, on a pu déterminer la densité d’états électronique DOS près de la bande d