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Article: Structural and defect characterization of GaAs and Al xGa 1-xAs grown at low temperature by molecular beam epitaxy
Title | Structural and defect characterization of GaAs and Al xGa 1-xAs grown at low temperature by molecular beam epitaxy |
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Authors | |
Issue Date | 1997 |
Publisher | American Institute of Physics. The Journal's web site is located at http://jap.aip.org/jap/staff.jsp |
Citation | Journal of Applied Physics, 1997, v. 81 n. 1, p. 190-198 How to Cite? |
Abstract | We have investigated the structural and defect characteristics of GaAs and Al xGa 1-xAs grown at low substrate temperature (250°C) by molecular beam epitaxy. Using x-ray diffraction we have observed an increase in lattice parameter for all as-grown layers, with the Al xGa 1-xAs layers showing a smaller expansion than the GaAs layer. However, infrared absorbtion measurements revealed that the concentration of neutral arsenic antisite defect, [As Ga] 0, was not significantly affected by aluminum content (x), with only a small reduction for x=0.36. Positron beam studies showed that the low temperature layers had a higher concentration of vacancy-related defects (∼10 17 cm -3) than the semi-insulating substrate, with the Al xGa 1-xAs layers having the highest values. After annealing (600°C, 15 min) the lattice constants relaxed to those of conventionally grown material and [As Ga] 0 was reduced in all cases, with the smallest reduction occurring for the x=0.36 layer, indicating that the Al atoms strengthen the lattice against excess arsenic incorporation and hold the arsenic antisite atoms more strongly in position. X-ray photoelectron spectroscopy showed that arsenic diffused out of the surface region and was replaced by oxygen, possibly due to an insufficient overpressure of forming gas during the anneal. This oxygen penetration was greater for the GaAs layer than for the Al xGa 1-xAs layers. Extra Raman peaks at 200 and 257 cm -1 confirmed that the surface was very disordered. There was, nevertheless, a large increase (4%) in the positron S parameter in the bulk of the annealed layers, suggesting the formation of vacancy clusters, whereas in the surface region we find evidence that As Ga diffusion proceeded at a faster rate in the x=0.36 than the x=0.2, in agreement with the vacancy-enhanced As Ga diffusion model. © 1997 American Institute of Physics. |
Persistent Identifier | http://hdl.handle.net/10722/174641 |
ISSN | 2023 Impact Factor: 2.7 2023 SCImago Journal Rankings: 0.649 |
ISI Accession Number ID | |
References |
DC Field | Value | Language |
---|---|---|
dc.contributor.author | Fleischer, S | en_HK |
dc.contributor.author | Beling, CD | en_HK |
dc.contributor.author | Fung, S | en_HK |
dc.contributor.author | Nieveen, WR | en_HK |
dc.contributor.author | Squire, JE | en_HK |
dc.contributor.author | Zheng, JQ | en_HK |
dc.contributor.author | Missous, M | en_HK |
dc.date.accessioned | 2012-11-26T08:46:39Z | - |
dc.date.available | 2012-11-26T08:46:39Z | - |
dc.date.issued | 1997 | en_HK |
dc.identifier.citation | Journal of Applied Physics, 1997, v. 81 n. 1, p. 190-198 | - |
dc.identifier.issn | 0021-8979 | en_HK |
dc.identifier.uri | http://hdl.handle.net/10722/174641 | - |
dc.description.abstract | We have investigated the structural and defect characteristics of GaAs and Al xGa 1-xAs grown at low substrate temperature (250°C) by molecular beam epitaxy. Using x-ray diffraction we have observed an increase in lattice parameter for all as-grown layers, with the Al xGa 1-xAs layers showing a smaller expansion than the GaAs layer. However, infrared absorbtion measurements revealed that the concentration of neutral arsenic antisite defect, [As Ga] 0, was not significantly affected by aluminum content (x), with only a small reduction for x=0.36. Positron beam studies showed that the low temperature layers had a higher concentration of vacancy-related defects (∼10 17 cm -3) than the semi-insulating substrate, with the Al xGa 1-xAs layers having the highest values. After annealing (600°C, 15 min) the lattice constants relaxed to those of conventionally grown material and [As Ga] 0 was reduced in all cases, with the smallest reduction occurring for the x=0.36 layer, indicating that the Al atoms strengthen the lattice against excess arsenic incorporation and hold the arsenic antisite atoms more strongly in position. X-ray photoelectron spectroscopy showed that arsenic diffused out of the surface region and was replaced by oxygen, possibly due to an insufficient overpressure of forming gas during the anneal. This oxygen penetration was greater for the GaAs layer than for the Al xGa 1-xAs layers. Extra Raman peaks at 200 and 257 cm -1 confirmed that the surface was very disordered. There was, nevertheless, a large increase (4%) in the positron S parameter in the bulk of the annealed layers, suggesting the formation of vacancy clusters, whereas in the surface region we find evidence that As Ga diffusion proceeded at a faster rate in the x=0.36 than the x=0.2, in agreement with the vacancy-enhanced As Ga diffusion model. © 1997 American Institute of Physics. | en_HK |
dc.language | eng | en_US |
dc.publisher | American Institute of Physics. The Journal's web site is located at http://jap.aip.org/jap/staff.jsp | en_HK |
dc.relation.ispartof | Journal of Applied Physics | en_HK |
dc.rights | Copyright 1997 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics, 1997, v. 81 n. 1, p. 190-198 and may be found at https://doi.org/10.1063/1.364105 | - |
dc.title | Structural and defect characterization of GaAs and Al xGa 1-xAs grown at low temperature by molecular beam epitaxy | en_HK |
dc.type | Article | en_HK |
dc.identifier.email | Beling, CD: cdbeling@hkucc.hku.hk | en_HK |
dc.identifier.email | Fung, S: sfung@hku.hk | en_HK |
dc.identifier.authority | Beling, CD=rp00660 | en_HK |
dc.identifier.authority | Fung, S=rp00695 | en_HK |
dc.description.nature | published_or_final_version | en_US |
dc.identifier.doi | 10.1063/1.364105 | - |
dc.identifier.scopus | eid_2-s2.0-0001451387 | en_HK |
dc.identifier.hkuros | 21262 | - |
dc.relation.references | http://www.scopus.com/mlt/select.url?eid=2-s2.0-0001451387&selection=ref&src=s&origin=recordpage | en_HK |
dc.identifier.volume | 81 | en_HK |
dc.identifier.issue | 1 | en_HK |
dc.identifier.spage | 190 | en_HK |
dc.identifier.epage | 198 | en_HK |
dc.identifier.isi | WOS:A1997WA94700029 | - |
dc.publisher.place | United States | en_HK |
dc.identifier.scopusauthorid | Fleischer, S=7103394445 | en_HK |
dc.identifier.scopusauthorid | Beling, CD=7005864180 | en_HK |
dc.identifier.scopusauthorid | Fung, S=7201970040 | en_HK |
dc.identifier.scopusauthorid | Nieveen, WR=6602585331 | en_HK |
dc.identifier.scopusauthorid | Squire, JE=7102094478 | en_HK |
dc.identifier.scopusauthorid | Zheng, JQ=16199204700 | en_HK |
dc.identifier.scopusauthorid | Missous, M=7007147933 | en_HK |
dc.identifier.issnl | 0021-8979 | - |