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  • 1
    Electronic Resource
    Electronic Resource
    Defects in electron irradiated GaP studied by positron lifetime spectroscopy (1995)
    Springer
    Applied physics 60 (1995), S. 541-544 
    Details
    ISSN: 1432-0630
    Keywords: 61.70 ; 61.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Defects induced by electron irradiation were investigated in GaP. The irradiation was performed at 15 K with an incident electron energy of 2 MeV and a fluence of 1018cm−2. Annealing experiments were carried out in the temperature range between 100 and 1000 K. Ga and P vacancies were detected after electron irradiation and the different annealing behaviour of the two types of vacancies was observed. The recovery stage between 100 and 400 K was attributed to the annealing of Ga vacancies and the recovery at temperatures above 900 K to the annealing of P vacancies. We also performed Hall measurements to determine the location of the Fermi level in the bandgap during the annealing. Two different ionization levels of the P vacancy were found which can be attributed to the transitions V P + /V P o and V P o /V P − . Temperature-dependent measurements were performed to study the effect of shallow positron traps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538526
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  • 2
    Electronic Resource
    Electronic Resource
    Mercury vacancy equilibria in Hg1−xCdxTe (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7563-7569 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental data of mercury vacancy equilibria in Hg1−xCdxTe for the compositions x=0.2 and x=0.3 are presented. In addition to common Hall-effect measurements, the composition x=0.2 is also studied by the positron annihilation technique. The results obtained are in good agreement with data published in the early eighties. A systematic discussion of the change of vacancy equilibria as well as conduction type for the composition interval x=0.2 to x=0.4 is given. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362412
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  • 3
    Electronic Resource
    Electronic Resource
    Defect identification in GaAs grown at low temperatures by positron annihilation (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8368-8379 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use positron annihilation to study vacancy defects in GaAs grown at low temperatures (LT–GaAs). The vacancies in as-grown LT–GaAs can be identified to be Ga monovacancies, VGa, according to their positron lifetime and annihilation momentum distribution. The charge state of the vacancies is neutral. This is ascribed to the presence of positively charged AsGa+ antisite defects in vicinity to the vacancies. Theoretical calculations of the annihilation parameters show that this assignment is consistent with the data. The density of VGa is related to the growth stoichiometry in LT–GaAs, i.e., it increases with the As/Ga beam equivalent pressure (BEP) and saturates at 2×1018 cm−3 for a BEP≥20 and a low growth temperature of 200 °C. Annealing at 600 °C removes VGa. Instead, larger vacancy agglomerates with a size of approximately four vacancies are found. It will be shown that these vacancy clusters are associated with the As precipitates formed during annealing. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373549
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  • 4
    Electronic Resource
    Electronic Resource
    Vacancies and deep levels in electron-irradiated 6H SiC epilayers studied by positron annihilation and deep level transient spectroscopy (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 3377-3382 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The annealing behavior of defects in n-type 6H SiC epilayers irradiated with 2 MeV electrons have been studied using positron annihilation and deep level transient spectroscopy. Vacancy-type defects are annealed at 500–700 °C and 1200–1400 °C. From the analysis of Doppler broadening spectra (core electron momentum distribution), the latter annealing process is attributed to the disappearance of complexes related to silicon vacancies and not to nearest neighbor divacancies. Among the observed deep levels, the E1/E2 levels show similar annealing behavior to that of positron annihilation centers above 1000 °C. It is thus proposed that the E1/E2 levels originate from complexes containing silicon vacancies. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1402144
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  • 5
    Electronic Resource
    Electronic Resource
    Annealing behavior of vacancies and Z1/2 levels in electron-irradiated 4H–SiC studied by positron annihilation and deep-level transient spectroscopy (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3950-3952 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Annealing behavior of vacancies and the Z1/2 levels in n-type 4H–SiC epilayers after 2 MeV electron irradiation has been studied using positron annihilation and deep-level transient spectroscopy. Isochronal annealing studies indicate that silicon vacancy-related defects are primarily responsible for positron trapping. The Z1/2 levels are the predominant deep centers after irradiation and subsequent annealing at 1200 °C. Both the positron-trapping rate at vacancies and the Z1/2 concentration decrease in a similar manner while annealing from 1200 to 1500 °C. It is thus proposed that the Z1/2 levels originate from silicon vacancy-related defects. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1426259
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  • 6
    Electronic Resource
    Electronic Resource
    Impurity gettering by vacancy-type defects in high-energy ion-implanted silicon at Rp /2 (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3932-3934 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Vacancy-type defects were studied after high-energy self-implantation of Si and subsequent rapid thermal annealing by means of a depth-resolution enhanced positron beam technique. Two different types of open-volume defects were found at a depth of Rp/2 and Rp, respectively. The defect type at Rp/2 is an agglomeration of point defects containing vacancies. This defect getters diffusing copper atoms. The vacancy-type defect observed in a depth of Rp could be connected to the interstitial loops formed there. The positron annihilation parameters suggest that this detected defect is not decorated by diffusing copper atoms. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1332814
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  • 7
    Electronic Resource
    Electronic Resource
    Study of defects in electron irradiated CuInSe2 by positron lifetime spectroscopy (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 71-78 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: CuInSe2 was studied in the as-grown state and after low-temperature (4 K) 2 MeV electron irradiation. The positron bulk lifetime of 235 ps was measured for the unirradiated sample. The positron bulk lifetime was theoretically calculated and is in good agreement with the experimental value. In addition, the defect-related lifetimes for mono-, di-, and trivacancies are theoretically determined. An increased average positron lifetime indicated after electron irradiation the appearance of open-volume defects, most probably of divacancy type. The disappearance of this defect was observed during annealing below 250 K. Other defects were formed leading to a divacancy signal at least stable up to 600 K in the temperature range above 450 K. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366703
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of the defect depth profile after saw cutting of GaAs wafers measured by positron annihilation (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 2255-2262 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Positron lifetime measurements and Doppler broadening spectroscopy using slow positrons were combined to investigate open-volume defects created by sawing wafers from GaAs ingots by a diamond saw cutter. It was found during step-by-step polishing that the depth distribution represents a wedgelike profile. The depth and the concentration of the defects introduced by the diamond saw depend on the advance of the saw blade. An isochronal annealing experiment was carried out to study the thermal stability of the observed defects. The positron lifetime of the dominant open-volume defect was estimated to be larger than 330 ps. It was concluded from this lifetime value and from the Doppler broadening parameters as well as from the annealing behavior that vacancy aggregates consisting of at least two vacancies are created by the sawing procedure. More extended defects such as microcracks were analyzed by scanning electron microscopy. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368291
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  • 9
    Electronic Resource
    Electronic Resource
    Ga vacancies in low-temperature-grown GaAs identified by slow positrons (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 638-640 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A systematic investigation of GaAs layers grown at low temperatures was carried out by means of positron annihilation. The vacancy defects in undoped as-grown material were identified to be mainly Ga vacancies (VGa) by comparing the annihilation parameters to those of Ga vacancies in highly Si-doped GaAs. The characteristic S parameter for positron annihilation in Ga vacancies was determined to be S(VGa)=1.024(1). The VGa concentration increases up to 1018 cm−3 by decreasing the growth temperature to 200 °C. The vacancy concentration can account for the compensation of AsGa+ antisites as was previously assumed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119814
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  • 10
    Electronic Resource
    Electronic Resource
    Study of vacancy defects in PbSe and Pb"1"-"xSn"xSe by positron annihilation
    Amsterdam : Elsevier
    Journal of Crystal Growth 131 (1993), S. 271-274 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(93)90423-T
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