Investigation of deep levels in rapid thermally annealed SiO2 capped n-GaAs grown by metalorganic chemical vapour deposition

Abstract

Defects created in rapid thermally annealed (RTA) SiO2-capped epitaxial GaAs layers grown by metal-organic chemical vapor deposition have been investigated by deep level transient spectroscopy. RTA introduced four electron traps S1 (Ec -0.23 eV), S2 (Ec-0.46eV), S3 (Ec -0.72eV), and S4 (Ec -0.74eV). S1 may be the so-called EL9 defect. We propose that S2 is a defect complex involving the Ga vacancy and Si dopant atoms, VGa-SiGa, and associate it with the EL5. S2 is introduced almost uniformly within the first 0.8 μm below the surface with an activation energy of 4.4 eV. S4 is most probably one of the EL2 family. The concentration of S4 decreased exponentially below the surface with a characteristic decay length ∼0.2 μm. The activation energy for the introduction of S4 is 2.5 eV.