An improved pulsed low-energy positron system

Willutzki, P.; Stormer, John C.; Kögel, G.; Sperr, P.; Britton, D.T.; Steindl, R.; Triftshäuser, W.

doi:10.1088/0957-0233/5/5/013

Cited by 60 publications

(16 citation statements)

References 9 publications

(1 reference statement)

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“…The former measures the time interval between birth g from 22 Na-source and the annihilation g and latter the distribution of the annihilation energy, which is broadened because of the momentum of electrons. In thin layers the positron lifetime spectrum can be measured by a pulsed positron beam [10,11].…”

Section: Methods and Measured Samplesmentioning

confidence: 99%

Gallium and nitrogen vacancies in GaN: Impurity decoration effects

Hautakangas

Ranki

Makkonen

et al. 2006

Physica B: Condensed Matter

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Section: Methods and Measured Samplesmentioning

confidence: 99%

Gallium and nitrogen vacancies in GaN: Impurity decoration effects

Hautakangas

Ranki

Makkonen

et al. 2006

Physica B: Condensed Matter

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“…33 In this experiment, the incident positron energy was varied from 1 to 20 keV at room temperature. About 1ϫ10 6 events were collected in each lifetime spectrum with a time resolution of 230 ps.…”

Section: Techniquesmentioning

confidence: 99%

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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“…For this purpose, a bunching unit [10,11] is connected to the positron generation system. In this mode, the positron beam with energy of 10 eV generated by the positron gun is transported to the bunching unit in the continus guiding magnetic field.…”

Section: Pulsing Systemmentioning

confidence: 99%