Donor levels of the divacancy-oxygen defect in silicon

Abstract

The elimination of divacancies (V 2 ) upon isochronal and isothermal annealing has been studied in oxygen-rich p-type silicon by means of deep level transient spectroscopy (DLTS) and high resolution Laplace DLTS. Divacancies were introduced into the crystals by irradiation with 4 or 6 MeV electrons. The temperature range of the divacancy disappearance was found to be 225-300 C upon 30 min isochronal annealing in the samples studied. A clear anti-correlation between the disappearance of V 2 and the appearance of two hole traps with activation energies for hole emission of 0.23 eV and 0.08 eV was observed. It is argued that these traps are related to the first and second donor levels of the divacancy-oxygen (V 2 O) complex, respectively. Significant electric field enhancement of the hole emission from the second donor level of the V 2 O center occurred in the diodes studied. It is shown that in the range of electric field from 4 Â 10 3 to 1.2 Â 10 4 V/cm the emission enhancement is associated with phonon-assisted tunnelling. V C 2014 AIP Publishing LLC. [http://dx.

Investigation of point and extended defects in electron irradiated silicon—Dependence on the particle energy

“…As shown in the literature, this defect is bi-stable, changing its configuration at ambient temperatures from a PHR configuration to a fourfold coordinated (FFC) one, 30 while it is stable up to 220 C. 32,33 It has been shown previously that the recovery of both DLTS signals (from V 3 ¼/À and V 3 À/0 ) is possible by injection of a high forward current (1 A at 20 C for 10 min). 28,30,31 If the V 3 defect is partly responsible for the leakage current, then both the leakage current and the defect concentration should have also a similar annealing behavior.…”

“…Among the multitude of radiation induced electrically active defects only some proved to have a direct impact on the "macroscopic" behavior of the sensors operating at ambient temperatures. These point-or extended-defects are labeled in the literature as: I p -a deep acceptor strongly generated in oxygen lean, standard float-zone material (STFZ) [22][23][24] and BD-a bistable thermal donor (TDD2) 24,26,27 strongly generated in oxygen rich float-zone material (DOFZ), both associated with point defects that are stable at room temperature and determining the N eff in silicon diodes irradiated with Co 60 g-rays; E(30K)-a shallow donor contributing to the a) R. Radu beneficial annealing after hadron irradiation, strongly generated in diodes irradiated with charged particles; 10,29 H(116K), H(140K), H(152K)-cluster-related hole traps with enhanced field emission (acceptors in the lower part of the Si bandgap), contributing fully with their concentration to N eff and causing the long term annealing effects (reverse annealing) in hadron irradiated silicon diodes; 10,29 the bistable E4 and E5 energy levels-identified with the double and single acceptor charge state of the V 3 defect in a configuration part of a hexagonal ring (PHR), respectively, [30][31][32][33] a defect contributing to the magnitude of the leakage current in the Si sensors and bipolar transistors upon irradiation with high energy particles. 28,31 The most important characteristics of these defects, including some features resulted from the present work, are summarized in Table I.…”

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

“…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.…”

“…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].…”