Deep trapping centres in n-GaAs surface barrier diodes for nuclear radiation detection

Deep level transient spectroscopy has been applied for the first time in the study of deep level trapping centres in n-GaAs nuclear radiation detectors. Devices from bulk and epitaxial material with net donor impurity densities from 5×1013 to 3×1016 cm¿3 have been studied and several common levels observed. The Poole-Frenkel effect has been identified in three levels (Ev+0.19 eV, Ec¿0.62 eV, Ec¿0.73 eV) in the epitaxial GaAs. A value for the Poole-Frenkel constant of ß = 4.7±1.4×10¿4 eV V¿¿ cm¿ was obtained for the Ec¿0.62 eV level, compared to the theoretical value for GaAs, 2.3×10¿4 eV V¿1/2 cm1/2.