Showing papers by "Stephen J. Pearton published in 1982"

A study of deep metal-related centres in germanium by capacitance spectroscopy

Abstract: Results are presented for deep energy states associated with Se, Te, Cd, Mg, Ti, Cr, Mn, Fe, Zr and Co diffused for 8–10 hr at ∼ 750°C into n - and p -type Ge (| N A – N D | = 4 × 10 12 − 6 × 10 13 cm −3 ). Defect centres with similar energies were measured for several of the metals, strengthening the view that many deep metal-related centres in Ge are structurally complex rather than simple substitutional or interstitial defects.

Hydrogen passivation of deep donor centres in high-purity epitaxial GaAs

Abstract: The passivation of deep donor centres in high-purity, liquid-phase-epitaxial n-GaAs (ND-NA = 8-10 × 1013 cm¯3) by reaction with atomic hydrogen has been observed using deep-level transient spectroscopy. Exposure to the hydrogen plasma for 3 h at 300°C neutralised 99% of the deep levels to a depth of approximately 7 µm.

Use of thermal annealing for radiation hardening of germanium to γ-rays

Abstract: Thermal annealing for extended periods (20-1000 hours) at moderately low temperatures (500–675°C) is shown to produce significant hardening to the γ-radiation induced EV + 0.23 eV and EV + 0.38 eV levels in Ge crystals grown by the Czochralski technique from silica crucibles. Annealed samples showed concentrations of these levels between 33–58% of those in untreated control samples, as measured by deep level transient spectroscopy. In some samples, heating to 500°C for 1 hour produced the same effect.

New gamma-radiation damage centres observed in germanium by deep level transient spectroscopy

Abstract: The dominant defect levels in γ-irradiated doped and high-purity Ge have been studied by transient capacitance spectroscopy. All p-type samples displayed acceptors at Ev + 0.23 eV and Ev+0.38 eV, whose capture cross-sections for holes were ∼10−14 cm2. In n-type samples a deep donor (Ec −0.42 ev) with electron capture cross-section ∼10−14 cm2 was observed in all but the highest purity material. Long-term room temperature annealing introduced two deep donors (Ec −0.36eV, Ec −0.20eV) into some n-type material; newly irradiated samples from the same crystals did not show these levels. In the n-type material, the loss of shallow donor states by electrically inactive complexing with vacancies was the compensation mechanism.

Deep level defects in gamma-ray irradiated ge doped with pb or sn

Abstract: Deep level transient spectroscopy has been used to investigate the electrical properties of deep defect states in γ-ray irradiated Ge doped with the isoelectronic elements Pb or Sn. Three deep levels are observed in the irradiated Pb-doped Ge (Ev +0.28 eV, Ec −0.33 eV, Ec −0.39 eV) and two deep levels observed in the Sn-doped Ge (Ev + 0.19 eV, Ec −0.15 eV). For the same γ-ray irradiation doses, Ge crystals grown from graphite crucibles and doped with Pb or Sn shows about two-thirds the total density of deep level defects observed in undoped Ge grown from synthetic quartz crucibles. All of the defect states observed were removed by a 1 hour, 250°C thermal anneal, and all but the Ec −0.39 eV state in the Pb-doped material were neutralized by exposure to a low pressure atomic hydrogen plasma.