Anneal induced transforms of radiation defects in hadron and - PowerPoint PPT Presentation

Anneal induced transforms of radiation defects in hadron and electron irradiated Si D.Meskauskaite 1 , E.Gaubas 1 , T.Ceponis 1 , J.Pavlov 1 , V.Rumbauskas 1 , J.Vaitkus 1 M.Moll 2 , F.Ravotti 2 , C.Gallrapp 2 L.Makarenko 3 1 Vilnius University, Institute of Applied Research 2 CERN 3 Belarusian State University Outline: • Motivation • Samples and irradiations, anneals • Temperature dependent carrier trapping lifetime (TDTL) • Results on n-type and p-type CZ Si irradiated by 6.6 MeV electrons • Results on n-type FZ and p-type CZ Si irradiated by 26 GeV/c protons • Results on n-type FZ and CZ Si irradiated by 300 MeV/c pions • Summary

Motivation • The better understanding of radiation damage of particle detectors is important in order either to extend sensor lifetime and their radiation hardness or to restore their functionality after degradation caused by irradiations. • One of the ways to recover detector operational features is heat treatment at technically acceptable temperatures. • Knowledge of evolution of the most harmful radiation defects under heat- treatment procedures is inevitable for development of the anneal technologies. • The radiation defects identification by applying the contact-less MW-PC measurements and TDTL analysis, when the standard contact methods (C-DLTS) become unsuitable due to the disordered structures and internal electric fields existing within heavily radiation damaged materials.

Samples and irradiations Type of irradiation Electrons Protons Pions Energy 6.6 MeV 24 GeV/c 300 MeV/c 10 16 -5 × 10 16 e/cm 2 10 12 -10 16 p/cm 2 10 11 -3 × 10 15 π + /cm 2 Fluence range Si material CZ n-Si CZ p-Si FZ n-Si CZ p-Si CZ n-Si FZ n-Si 10 15 cm -3 3  10 15 cm  3 10 12 cm -3 10 12 cm -3 10 12 cm -3 10 12 cm -3 Dopant concentration 4.5  cm 4.5  cm >3 k  cm 10 k  cm >3 k  cm >3 k  cm Resistivity

Samples and irradiations Type of irradiation Electrons Protons Pions Energy 6.6 MeV 24 GeV/c 300 MeV/c 10 16 -5 × 10 16 e/cm 2 10 12 -10 16 p/cm 2 10 11 -3 × 10 15 π + /cm 2 Fluence range Si material CZ n-Si CZ p-Si FZ n-Si CZ p-Si CZ n-Si FZ n-Si 10 15 cm -3 3  10 15 cm  3 10 12 cm -3 10 12 cm -3 10 12 cm -3 10 12 cm -3 Dopant concentration 4.5  cm 4.5  cm >3 k  cm 10 k  cm >3 k  cm >3 k  cm Resistivity Anneals • The isochronal anneals for 24 hours have been performed at the temperatures in the range of 80 ˚ -280 ˚ C. • The hadron irradiated samples were isothermally (at 80 ˚C) annealed up to 5 hours before isochronal (24 h) anneals.

Temperature dependent carrier trapping lifetime (TDTL) T peak for which the largest K tr , ascribed to a single type The as-recorded MW-PC trapping centres, is obtained, can be found by solving the transients in CZ Si sample transcendental equations: irradiated with fluence 2 E    2 / 3 tr T A exp( ) , for fixed n const 4  10 16 e/cm 2 after heat peak C 3 kT peak treatment 280 ˚C at 34 34 E   tr T B 33 exp( ) , for n ( T ) different scan peak 33 kT peak temperatures. A=  n C /K K=N C,V  T -3/2 B=(  300  300 -4.25  F/K) Simulated trapping  n(T) K tr1 coefficients (K tr ) as a N C,e,Ntr1 (T) K tr2 3 10 19 10 N C,e,Ntr2 (T) K sum (b) function of temperature -3 ) 16 E tr2 =0.23 eV Peak temperature (within 10 for trapping level with  n, N C,e,Ntr (cm 300 (d) 2 10 13 TDTL spectrum) dependence 10 activation energy of K tr T peak (K) 10 on trapping centre activation 10 0.4eV and 0.23eV in Si. 200  n C E tr1 =0.4 eV 1 7 A=10 -1 energy (E tr ) simulated for the 10 N C,e,Ntr (T) - the effective 10 A=10 -4 4 fixed ∆ n C =const and density of band states for 100  n(T) 10 B=10 -1 temperature varied ∆n(T ) 0 1 trapped carriers, ∆n(T) - 10 10 B=10 -4 100 200 300 400 500 0 excess carrier density the excess carrier density. T (K) 0.0 0.1 0.2 0.3 0.4 0.5 E tr (eV) E. Gaubas, E. Simoen and J. Vanhellemont, Review-Carrier lifetime spectroscopy for defect characterization in semiconductor materials and devices, ECS J. Solid State Sci. Technol. 5, (2016) P3108.

Results on n-type and p-type CZ Si irradiated by 6.6 MeV electrons Cz Si irradiated by electrons: 8 n-type: + - V 2 V 2  =1  10 16 cm -2 • The radiation induced defects, ascribed C-DLTS signal (pF) 16 cm -2  =5  10 o C: Annealed T an =280 to VO, V 2 O. V 3 O and VP complexes, TD 6 C i O i  =1  10 16 cm -2 H related 16 cm -2 and to H related defects have been  =5  10 p-type: 4 16 cm -2  =1  10 observed in the electron irradiated n- VO 16 cm -2 V 2 O  =5  10 type Cz-Si samples. o C: Annealed T an =280 16 cm -2  =1  10 2 B i C s 16 cm -2  =5  10 VOC + V 3 O V 2 O TD TD VP • The hydrogen, oxygen and carbon related 0 40 80 120 160 200 240 280 complexes of V 2 O, VOC, V 3 O, B i C s , C i O i , + and TD defects have been T (K) divacancy V 2 observed in the electron irradiated p- • No peaks in low temperature wing were type Cz-Si samples. observed in heavily irradiated n- and p-type CZ samples. This result can be explained by the low effective doping concentration in heavily irradiated material.

Results on n-type and p-type CZ Si irradiated by 6.6 MeV electrons T an =180  C T an =280  C Experiment, Simulations Experiment, Simulations Cz Si irradiated by electrons: 8  R ,  tr,i single trap  R ,  tr,i single trap n-type: + - V 2 V 2 80  =1  10 16 cm -2  tr ,  tr (  traps )  tr ,  tr (  traps ) VO C-DLTS signal (pF) 16 cm -2  =5  10 CZ n-Si o C: Annealed T an =280 6 H related 16 e/cm 2  =4  10 60 C i O i  =1  10 16 cm -2 =  R ,  tr (  s) H related V 2 16 cm -2  =5  10 E=0.3 eV V 2 p-type: - V 3 O 4 16 cm -2  =1  10 V 3 O 40 VO 16 cm -2 V 2 O  =5  10 o C: Annealed T an =280 16 cm -2  =1  10 2 B i C s 20 16 cm -2  =5  10 VOC + V 3 O V 2 O TD TD VP 0 0 40 80 120 160 200 240 280 120 160 200 240 280 T (K) T (K) • No peaks in low temperature wing were • Application of the TDTL technique allowed to observed in heavily irradiated n- and p-type identify the trapping centres appeared after CZ samples. This result can be explained by heat treatment at T an ≥ 80 ˚C even in heavily the low effective doping concentration in irradiated samples. heavily irradiated material.

Results on n-type FZ and p-type CZ Si irradiated by 26 GeV/c protons DLTS signal (arb. units) = • DLTS V 2 measurement are not 13 p/cm 2  =1  10 FZ n-Si 0.3 14 p/cm 2  =1  10 o C 24h T an =250 suitable for p-type CZ Si samples H related irradiated by 26 GeV/c protons, 0.2 due to the low concentration of H related the effective doping. 0.1 V related VO - TD V 2 V related 0.0 50 100 150 200 250 T (K) • The predominant peaks for the n-type FZ Si samples are attributed to V- and H-related defects. • The application of DLTS technique for the p-type CZ Si samples is limited due to low effective doping concentration.

Results on n-type FZ and p-type CZ Si irradiated by 26 GeV/c protons  =1  10 13 p/cm 2  =5  10 13 p/cm 2 E xperiment, Simulations E xperiment , Simulations DLTS signal (arb. units)  R ,  tr,i single trap  R ,  tr,i single trap 12 = V 2 13 p/cm 2  tr ,  tr (  traps )  tr ,  tr (  traps )  =1  10 FZ n-Si 0.3 14 p/cm 2  =1  10 o C 24h T an =250 H related VO CZ p-Si  R ,  tr (  s) = V 8 T an = 200  C 24h 2 0.2 H related H related 4 0.1 V related VO - TD V 2 V related 0 0.0 120 160 200 240 280 50 100 150 200 250 T (K) T (K) = , H-related • The predominant peaks for the n-type FZ Si • As deduced using TDTL, the V 2 samples are attributed to V- and H-related and VO complexes are predominant radiation defects. defects in the p-type CZ Si. • The application of DLTS technique for the p-type • The TDTL spectroscopy is a reliable tool for CZ Si samples is limited due to low effective tracing of the radiation defect evolution for doping concentration. the range of elevated fluences.

Results on n-type FZ and CZ Si irradiated by 300 MeV/c pions DLTS signal (arb. units) 1.5 • The similarity between DLTS spectra, o C 24h T an =250 H related FZ n-Si: 13  /cm 2 obtained for rather low fluence irradiations  =1  10 CZ n-Si: by protons and pions, indicate that the 14  /cm 2  =1  10 1.0 H related irradiation with various type penetrative VO hadrons induce the same defects. = V 2 0.5 V related TD - V 2 0.0 50 100 150 200 250 T (K) • VO, double charged di-vacancy (V 2 = ), H-related and V-related defects are dominant defects in CZ n-Si samples after heat treatment at 250 ˚C . - defects are dominant defects in the • TD and V 2 FZ n-Si samples after heat treatment at 250 ˚C .