Shallow positron traps in GaAs

Saarinen, K.; Hautojärvi, P.; Vehanen, A.; Krause, R.; Dlubek, G.

doi:10.1103/physrevb.39.5287

Cited by 143 publications

(62 citation statements)

References 23 publications

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“…31 The concentration of impurities is low in our MBE-grown layers whereas Ga As antisites are not expected with the strongly As-rich stoichiometry of LT-GaAs. In a recent theoretical study, Landman et al 55 found a low formation energy for a split As interstitial which could, therefore, be an abundant defect in the strongly As-rich LTGaAs.…”

Section: ϫmentioning

confidence: 69%

“…The annihilation parameters for such defects are close to the bulk values but they can trap positrons only at low temperatures (TϽ150 K͒ in their shallow potential. 31 The presence of such defects would be detected as a strong decrease of S towards S b with decreasing temperature. This is not found.…”

Section: Revealing Neutral Ga Vacancy Complexes By Temperature-depmentioning

confidence: 99%

“…30 In addition to vacancies, positrons may be trapped in the attractive potential of negatively charged ions at low temperatures (Tр150 K͒. 31 Also, positron trapping at negatively charged vacancies increases with decreasing temperature but is independent on temperature for neutral vacancies. 32 Therefore, PAS measurements as a function of temperature can be used to derive information on the charge state of vacancies as well as on the presence of negative ions.…”

Section: B Positron Annihilationmentioning

confidence: 99%

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Defect identification in GaAs grown at low temperatures by positron annihilation

Gebauer¹,

Börner

Krause‐Rehberg

et al. 2000

Journal of Applied Physics

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We use positron annihilation to study vacancy defects in GaAs grown at low temperatures ͑LT-GaAs͒. The vacancies in as-grown LT-GaAs can be identified to be Ga monovacancies, V Ga , 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 As Ga ϩ 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 V Ga is related to the growth stoichiometry in LT-GaAs, i.e., it increases with the As/Ga beam equivalent pressure ͑BEP͒ and saturates at 2ϫ10 18 cm Ϫ3 for a BEPу20 and a low growth temperature of 200°C. Annealing at 600°C removes V Ga . 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.

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Section: ϫmentioning

confidence: 69%

Section: Revealing Neutral Ga Vacancy Complexes By Temperature-depmentioning

confidence: 99%

Section: B Positron Annihilationmentioning

confidence: 99%

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Defect identification in GaAs grown at low temperatures by positron annihilation

Gebauer¹,

Börner

Krause‐Rehberg

et al. 2000

Journal of Applied Physics

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“…The temperature dependence of positron trapping can determine the charge state of vacancy-related defects 8 and can also provide evidence on the presence of acceptor point defects without open volume such as substitutional impurities. 9 The lifetime of the localized positron state is sensitive to the size of the open volume, and the chemical nature of the near neighbor atoms dominates the electron momentum distribution sampled by the positron in the high momentum region. These can be measured using positron annihilation lifetime spectroscopy (PALS) and coincidence Doppler broadening spectroscopy (CDBS), respectively, and the results from both can be compared to DFT calculations.…”

mentioning

confidence: 99%

“…15,16 This temperature dependence provides clear evidence for trapping to defects with a small binding energy for positrons, and the associated positron states exhibit a lifetime similar to the bulk, perfect lattice, lifetime value, s B . 9,15 The fit to the STM for one vacancy defect (s v ¼ 330 ps) with one shallow binding energy trap (s st ¼ s B ¼ 285 ps), 15 both negatively charged, is shown in Fig. 1.…”

mentioning

confidence: 99%

Characterization of point defects in CdTe by positron annihilation spectroscopy

El-Sharkawy

Kanda

Abdel-Hady

et al. 2016

Applied Physics Letters

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Positron lifetime measurements on CdTe 0.15% Zn-doped by weight are presented, trapping to monovacancy defects is observed. At low temperatures, localization at shallow binding energy positron traps dominates. To aid defect identification density functional theory, calculated positron lifetimes and momentum distributions are obtained using relaxed geometry configurations of the monovacancy defects and the Te antisite. These calculations provide evidence that combined positron lifetime and coincidence Doppler spectroscopy measurements have the capability to identify neutral or negative charge states of the monovacancies, the Te antisite, A-centers, and divacancy defects in CdTe.

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