Identification of a Br-correlated bandgap state in GaAs by radiotracer spectroscopy

A deep energy level of bromine in the bandgap of GaAs was determined by means of Radiotracer deep-level transient spectroscopy (DLTS) measurements. For this purpose, the radioactive isotope Br-77 was implanted in p-type as well as in n-type GaAs. In the course of repeated DLTS measurements at n-type GaAs, the spectra are dominated by the occurrence of one bandgap state with the trap parameters E-t=E-C-0.45(2) eV and sigma=2x10(-14) cm(2). This level vanishes on time scales of the nuclear half-life of the elemental transmutation from Br-77 to Se-77 (T-1/2=57 h). Thereby, a definite correlation can be drawn between the observed bandgap state and a Br-correlated defect.