Oxygen-related 1-platinum defects in silicon: An electron paramagnetic resonance study

Abstract

A monoclinic 1-platinum defect recently detected was investigated more thoroughly by electron paramagnetic resonance ͑EPR͒. The defect is one of the dominating defects in platinum doped silicon. With a perfect reproducibility it is observed in samples prepared from n-type silicon as well as from p-type silicon, in float zone ͑FZ͒ silicon as well as in Czochralski ͑Cz͒ silicon. Its concentration varies with the conditions of preparation and nearly reaches that of isolated substitutional platinum in Cz silicon annealed for 2 h at 540°C after quenching from the temperature of platinum diffusion. Because of its concentration which in Cz-Si exceeds that in FZ-Si the defect is assumed to be oxygen-related though a hyperfine structure with 17 O could not be resolved. The defect causes a level close to the valence band. This is concluded from variations of the Fermi level and from a discussion of the spin Hamiltonian parameters. In photo-EPR experiments the defect is coupled to recently detected acceptorlike self-interstitial related defects ͑SIRDs͒; their level position turns out to be near-midgap. These defects belong to the lifetime limiting defects in Pt-doped Si.

Two-platinum-atom complex defects in silicon - an electron paramagnetic resonance study

“…We will refer to such samples as 'quenched after annealing with an uncovered surface'. It is suggested that as a result of this treatment the supersaturation with self-interstitials has been removed [10,20]. Some of the complex defects to be discussed in this paper are not formed in these samples.…”

“…The formation of certain complexes depends on the presence of additional defects which are assumed to be self-interstitials. In such samples various typical phenomena related to specific defects were detected [10,20]. Therefore, two types of sample were prepared and compared.…”

“…A continuous-flow cryostat from Oxford Instruments was applied. It was slightly modified in order to shield the sample from thermal radiation emitted by the walls of the EPR cavity [10]. In photo-EPR experiments the sample inside the quartz walls of the cryostat was illuminated through a quartz lens and the grid of the Bruker universal rectangular resonator.…”

“…The limiting of the carrier lifetime in silicon by doping with platinum was attributed for decades to Pt s , but has more recently been attributed to complex platinum-related defects [7][8][9]. The electrical levels of complex platinum-related defects differ substantially from the levels of Pt s [10]. This is a reason for investigating complex Pt-related defects.…”

The Interaction of Hydrogen with Deep Level Defects in Silicon

“…For example, DLTS measurements [179,180,181,182] on Pt doped n-Si have revealed a deep electron trap, located near the surface, with a level at ∼ E c − 0.50 eV and which plays an important part in limiting the lifetime of minority carriers. The assignment of this level has been very controversial and there are several suggestions of models for the defect responsible: Pt-Pt pairs [183,184], Pt-O pairs [181,185,186] and Pt-vacancy. However, very recently, Sachse et al [178] have argued that this mid-gap level arises from a defect involving Pt and hydrogen.…”