Formation of donor and acceptor states of the divacancy–oxygen centre in p-type Cz-silicon

Abstract

The formation of the divacancy-oxygen centre (V(2)O) in p-type Czochralski-grown silicon has been investigated by means of deep level transient spectroscopy (DLTS). The donor state (+/0) of V(2)O is located at ~E(v) + 0.23 eV (E(v) denotes the valence band edge) and emerges during heat treatment above 200 °C at the expense of the divacancy centre (V(2)). A concurrent transition takes place between the single-acceptor states of V(2) and V(2)O, as unveiled by the injection of electrons through optical excitation during the trap filling sequence of the DLTS measurements. Further, a defect with an energy level at ~E(v) + 0.09 eV evolves in close correlation with the growth of V(2)O but at a factor of ~5-6 lower in concentration. In the literature, the E(v) + 0.09 eV level has previously been attributed to a double-donor state of V(2)O but this assignment can be ruled out by the present data favouring a complex formed between migrating V(2) centres and a competing interstitial oxygen trap. In addition, a level at ~E(v) + 0.24 eV occurs also during the heat treatment above 200 °C and is tentatively assigned to the trivacancy-oxygen centre (V(3)O).

Donor levels of the divacancy-oxygen defect in silicon

“…18 The assignment of the above level to V 2 O has, however, been questioned recently. 19,20 Bearing in mind that the V 2 O center is a technologically important defect, which is thought to be responsible for the degradation of silicon based particle detectors, 21 we have carried out a detailed study of divacancy annealing in oxygen-rich p-type Si crystals and obtained conclusive information on electronic properties of the donor levels of the V 2 O defect.…”

Influence of Divacancy-Oxygen Defects on Recombination Properties of n-Si Subjected to Irradiation and Subsequent Annealing

“…3) testifies to the formation of either VO complexes (the major recombination centers after 60 Co -irradiation) or more efficient recombination centers. The temperature interval 180-300 ∘ C corresponds to the annealing interval of V 2 in Cz and DOFZ Si [9][10][11][12][13][14][15][16]. The efficiency of the VO center formation in 60 Co -irradiated Cz -Si specimens at room temperature is approximately two orders of magnitude higher than that of the V 2 formation [1,23].…”

“…Two new levels in -Si located at ∼ c − 0.23 eV and ∼ c − 0.47 eV were associated with doubly and singly charged acceptor states of V 2 O [9][10][11][12]. A new level at ∼ + 0.23 eV in -Si was identified as a donor state of V 2 O(+/0) [13][14][15][16]. At the same time, the level at ∼ + 0.08 eV is considered as V 2 O(2+/+) [14,16].…”

“…However, the positions of its electron levels in the forbidden band were discovered recently, when V 2 O was started to be considered as the main candidate responsible for the degradation of silicon detectors of ionizing particles [7,8]. Now, it was found [9][10][11][12][13][14][15][16] that the annealing of irradiated Cz or diffusion oxygenated float-zone (DOFZ) silicon in the temperature interval 200-300 ∘ C leads to the interaction between a mobile divacancy V 2 and an interstitial oxygen atom O . As a result of this interaction, a V 2 O defect is formed, which is annealed at temperatures of about 300-350 ∘ C. The transformation V 2 → V 2 O occurs with a proportionality of 1 : 1.…”

Lifetime Control in Irradiated and Annealed Cz n‐Si: Role of Divacancy‐Oxygen Defects

“…The V 2 O was first identified as an irradiation‐induced defect in Cz silicon after high‐dose electron irradiation . Later, it was shown that V 2 O can be formed in low‐dose irradiated Cz and diffusion‐oxygenated float‐zone (DOFZ) silicon after annealing above 200 °C when a mobile divacancy (V 2 ) is trapped by interstitial oxygen (O i ) atom (V 2 + O i → V 2 O) . This defect remains stable up to ≈300 °C.…”