Abstract
We have grown a multilayer structure of GaAs and AlxGa1-xAs (x = 0.25) by molecular beam epitaxy at low substrate temperature (250°C) in order to investigate the effects of annealing on arsenic precipitation and vacancy-defect formation. The as-grown heterostructure contained ∼5 × 1017 cm-3 gallium vacancies, but information about the individual layers was lost because the layer width ( ∼ 45 nm) was smaller than the average positron diffusion length ( ∼ 70 nm). Annealing at 500 and 600°C showed increases in the S-parameter (above the bulk value) of ∼2.5% and ∼1.5%, respectively, smaller than for a single LT-GaAs layer (∼3-4%). We explain this phenomenon by suggesting that the excess arsenic which migrates from the material with the higher precipitate/matrix energy (LT-AlxGa1-xAs) reduces the gallium vacancy concentration in the LT-GaAs and hence the S-parameter. This hypothesis is supported by SIMS data which shows a build-up of As in the LT-GaAs layers, and TEM images which indicate that arsenic precipitation occurs to a greater extent in the LT-GaAs than in the LT-AlxGa1-xAs.
| Original language | English |
|---|---|
| Pages (from-to) | 53-61 |
| Number of pages | 9 |
| Journal | Journal of Crystal Growth |
| Volume | 196 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 1 1999 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Condensed Matter Physics
- Inorganic Chemistry
- Materials Chemistry
Cite this
A study of the vacancy-defect distribution in a GaAs/AlxGa1-xAs multi-layer structure grown at low temperature. / Fleischer, S.; Surya, C.; Hu, Y. F.; Beling, C. D.; Fung, S.; Smith, T. L.; Moulding, K. M.; Missous, M.
In: Journal of Crystal Growth, Vol. 196, No. 1, 01.01.1999, p. 53-61.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A study of the vacancy-defect distribution in a GaAs/AlxGa1-xAs multi-layer structure grown at low temperature
AU - Fleischer, S.
AU - Surya, C.
AU - Hu, Y. F.
AU - Beling, C. D.
AU - Fung, S.
AU - Smith, T. L.
AU - Moulding, K. M.
AU - Missous, M.
PY - 1999/1/1
Y1 - 1999/1/1
N2 - We have grown a multilayer structure of GaAs and AlxGa1-xAs (x = 0.25) by molecular beam epitaxy at low substrate temperature (250°C) in order to investigate the effects of annealing on arsenic precipitation and vacancy-defect formation. The as-grown heterostructure contained ∼5 × 1017 cm-3 gallium vacancies, but information about the individual layers was lost because the layer width ( ∼ 45 nm) was smaller than the average positron diffusion length ( ∼ 70 nm). Annealing at 500 and 600°C showed increases in the S-parameter (above the bulk value) of ∼2.5% and ∼1.5%, respectively, smaller than for a single LT-GaAs layer (∼3-4%). We explain this phenomenon by suggesting that the excess arsenic which migrates from the material with the higher precipitate/matrix energy (LT-AlxGa1-xAs) reduces the gallium vacancy concentration in the LT-GaAs and hence the S-parameter. This hypothesis is supported by SIMS data which shows a build-up of As in the LT-GaAs layers, and TEM images which indicate that arsenic precipitation occurs to a greater extent in the LT-GaAs than in the LT-AlxGa1-xAs.
AB - We have grown a multilayer structure of GaAs and AlxGa1-xAs (x = 0.25) by molecular beam epitaxy at low substrate temperature (250°C) in order to investigate the effects of annealing on arsenic precipitation and vacancy-defect formation. The as-grown heterostructure contained ∼5 × 1017 cm-3 gallium vacancies, but information about the individual layers was lost because the layer width ( ∼ 45 nm) was smaller than the average positron diffusion length ( ∼ 70 nm). Annealing at 500 and 600°C showed increases in the S-parameter (above the bulk value) of ∼2.5% and ∼1.5%, respectively, smaller than for a single LT-GaAs layer (∼3-4%). We explain this phenomenon by suggesting that the excess arsenic which migrates from the material with the higher precipitate/matrix energy (LT-AlxGa1-xAs) reduces the gallium vacancy concentration in the LT-GaAs and hence the S-parameter. This hypothesis is supported by SIMS data which shows a build-up of As in the LT-GaAs layers, and TEM images which indicate that arsenic precipitation occurs to a greater extent in the LT-GaAs than in the LT-AlxGa1-xAs.
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UR - http://www.scopus.com/inward/citedby.url?scp=0032784885&partnerID=8YFLogxK
U2 - 10.1016/S0022-0248(98)00608-3
DO - 10.1016/S0022-0248(98)00608-3
M3 - Article
VL - 196
SP - 53
EP - 61
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
IS - 1
ER -