Point defect states in Sb-doped germanium

Defect states in n-type Sb-doped germanium were investigated by deep-level transient spectroscopy. Cobalt-60 gamma rays were used to generate isolated vacancies and interstitials which diffuse and react with impurities in the material to form four defect states (E₃₇, E₃₀, E₂₂, and E₂₁) in the upper half of the bandgap. Irradiations at 77 K and 300 K as well as isothermal anneals were performed to characterize the relationships between the four observable defects. E₃₇ is assigned to the Sb donor-vacancy associate (E-center) and is the only vacancy containing defect giving an estimate of 2 × 10¹¹cm⁻³ Mrad⁻¹ for the uncorrelated vacancy-interstitial pair introduction rate. The remaining three defect states are interstitial associates and transform among one another. Conversion ratios between E₂₂, E₂₁, and E₃₀ indicate that E₂₂ likely contains two interstitials