Formation of a Bistable Interstitial Complex in Irradiated p‐Type Silicon

Makarenko, Leonid; Lastovski, S. B.; Yakushevich, H. S.; Gaubas, E.; Pavlov, J.; Kozlovski, V. V.; Moll, M.; Pintilie, I.

doi:10.1002/pssa.201900354

Cited by 8 publications

(14 citation statements)

References 30 publications

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“…in the material, where the ratio of the capture radii of interstitials at boron (k IB ) and at carbon (k IC ) has been determined to be k IB /k IC ≈ 7 [25]. The absolute boron removal rate g B is thus given by the generation rate g BiOi of the B i O i defect which can be estimated to be…”

Section: Discussionmentioning

confidence: 99%

“…In order to understand the microscopic origin of the above described acceptor removal effects dedicated defect characterization campaigns on irradiated p-type silicon devices employing Deep Level Transient Spectroscopy (DLTS), Thermally Stimulated Current (TSC) and other techniques have been initiated within the RD50 collaboration [23,24,25]. A schematic understanding of…”

Section: Defect Kinetics and Defect Characterizationmentioning

confidence: 99%

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Acceptor removal - Displacement damage effects involving the shallow acceptor doping of p-type silicon devices

Moll¹

2020

Proceedings of the 28th International Workshop on Vertex Detectors — PoS(Vertex2019)

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New sensor technologies are under development to cope with the ever increasing requirements for high energy physics (HEP) detectors. For the High-Luminosity LHC (HL-LHC) and the Future Circular Collider (FCC) higher radiation hardness, improved timing performance and lower cost large area detector technologies are essential. Recent developments of p-type silicon planar sensors, sensors with intrinsic gain for timing applications and monolithic sensors are examples for next generation detector technologies. A commonality of these new sensors is the use of boron doped p-type silicon, while present HEP sensors are essentially based on n-type silicon. Consequently, radiation effects in p-type silicon have been less studied in the detector community, but are now of high relevance. In this paper, we review radiation effects in p-type silicon devices with a focus on acceptor removal effects. In p-type silicon exposure to radiation causes an apparent deactivation of the dopant. This socalled acceptor removal effect is for example evidenced by an initial decrease of depletion voltage in p-type sensors with rising particle fluence, while after exposure to higher fluences the device behavior is dominated by other radiation induced effects. Low Gain Avalanche Detectors (LGADs) are the baseline technology for future solid-state timing layers at the HL-LHC. Their good timing performance is based on the intrinsic amplification of the signal by impact ionization in a highly doped p-type gain layer. Radiation effects reduce the active boron concentration in the gain layer and lead to a reduction in field strength and consequently a loss of intrinsic signal amplification, thus limiting the radiation hardness of this technology. Monolithic detectors, especially High Voltage CMOS, are another technology affected by acceptor removal, as the bulk silicon used for the sensor is typically of p-type. We review the impact of radiation damage on the depleted volume as function of the initial boron concentration and the corresponding change in signal charge and device performance. The origin of the radiation induced deactivation of the boron acceptor is found in the creation of defects that contain boron, that is consequently no longer acting as shallow dopant. Defect spectroscopy techniques like Thermally Stimulated Currents (TSC) and Deep Level Transient Spectroscopy (DLTS) allow detecting these levels, help to understand the defect formation kinetics on the microscopic level and open the door to defect engineering approaches to mitigate the acceptor removal effect. Latest results of the CERN RD50 collaboration in this research field are reviewed.

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Section: Discussionmentioning

confidence: 99%

Section: Defect Kinetics and Defect Characterizationmentioning

confidence: 99%

Acceptor removal - Displacement damage effects involving the shallow acceptor doping of p-type silicon devices

Moll¹

2020

Proceedings of the 28th International Workshop on Vertex Detectors — PoS(Vertex2019)

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“…The evolution of radiation defects in p -type Si introduced by electron beam is rather well understood [ 18 , 22 ]. Thereby, identification of the most resolved traps in Si can be reliably implemented based on activation energy values reported in the literature.…”

Section: Recorded Dlt Spectra and Extracted Trap Parametersmentioning

confidence: 99%

“…The trap with the activation energy of 0.080 eV (E 1 in Table 1 ) is attributed to the double interstitial and oxygen (I 2 O) complex [ 18 ]. The 0.100 eV (E 2 ) level can be assigned to a triple vacancy (V 3 ) [ 18 ]. The origin of the E 3 trap is not clear, however, it might be related to vacancy (V) [ 23 ].…”

Section: Recorded Dlt Spectra and Extracted Trap Parametersmentioning

confidence: 99%

“…In some cases, radiation damage to the Si 1−x Ge x devices related to the introduction of radiation defects can be “removed” by annealing [ 17 ]. This can be implemented by the atomic reconfiguration of the crystal structure during material annealing [ 18 ]. However, the radiation defect spectrum in p -type Si 1−x Ge x detectors has been poorly examined.…”

Section: Introductionmentioning

confidence: 99%

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Study of Radiation-Induced Defects in p-Type Si1−xGex Diodes before and after Annealing

et al. 2020

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In this work, electrically active defects of pristine and 5.5 MeV electron irradiated p-type silicon–germanium (Si1−xGex)-based diodes were examined by combining regular capacitance deep-level transient spectroscopy (C-DLTS) and Laplace DLTS (L-DLTS) techniques. The p-type SiGe alloys with slightly different Ge contents were examined. It was deduced from C-DLTS and L-DLTS spectra that the carbon/oxygen-associated complexes prevailed in the pristine Si0.949Ge0.051 alloys. Irradiation with 5.5 MeV electrons led to a considerable change in the DLT spectrum containing up to seven spectral peaks due to the introduction of radiation defects. These defects were identified using activation energy values reported in the literature. The double interstitial and oxygen complexes and the vacancy, di-vacancy and tri-vacancy ascribed traps were revealed in the irradiated samples. The interstitial carbon and the metastable as well as stable forms of carbon–oxygen (CiOi* and CiOi) complexes were also identified for the electron-irradiated SiGe alloys. It was found that the unstable form of the carbon–oxygen complex became a stable complex in the irradiated and the subsequently annealed (at 125 °C) SiGe samples. The activation energy shifts in the radiation-induced deep traps to lower values were defined when increasing Ge content in the SiGe alloy.

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