Deep Electron Traps in Undoped GaAs Grown by MOCVD

Deep electron traps in undoped GaAs grown by metalorganic chemical vapor deposition (MOCVD) have been investigated using DLTS measurement. Five electron traps were detected. The dominant trap shows an activation energy of 0.80±0.02 eV, which is probably the same level as EL2 in conventional VPE GaAs layers. The remaining four traps were only observed in samples grown with a particular trimethylgallium (TMG) source, and were below the detection limit (5×1011-5×1012 cm-3) with other TMG sources. These results strongly indicate that the four traps are due to impurities in the source material.