Photo-induced migration of chalcogen atoms in II-VI semiconductors
| Project/Area Number |
05640378
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Osaka University |
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Principal Investigator |
SUGAI Shunji Osaka University, Faculty of Science, Associate Professor, 理学部, 助教授 (50028263)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1994: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1993: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | II-VI semiconductor / Photo-induced precipitation / Photo-induced structural change / Raman scattering / Phonon / スモール・ポーラロン / オフセンター・セルフトラップ・エキシトン |
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| Research Abstract |
Various kins of anomalos phonon peaks are observed in the Raman spectra in II-IV semiconductors. They are longitudinal optical phonons and ixtrinsic phonons due to the deformed structure by photo-induced atomic migration. The surface preparation (cleavage, mechanical polishing, and chemical etching), incident laser wavelength, laser power, polarization configuration dependences of the Raman spectra of CdTe and Cd_<1-x>Zn_xTe are investigated at the temperature range of 25 K to 350K in He atmosphere. The bulk properties are following. (1) Resonant 4th--8th-order multi-phonon scattering of the LO phonon is observed for the parallel polarization (e_i||e_s) of the incident and the scattered light. The intensity is strongly enhanced when the scattered light energy is the same as the luminescence energy at low temperatures. The enhancement decreases in accordance with the luminescence intensity upon heating. (2) The peaks at 72,108, and 187cm^<-1> appear and increase in intensity upon heating for e_i||e_s||<1,1,0>and<0,0,1>. The properties observed only on the cleaved surface are as follows. (1) Small peaks are observed at 30 and 56cm^<-1> at all temperatures for e_i||e_s||<1,1,0>. (2) Just after the cleavage a new peak appears at 147cm^<-1> and grows up above 150 K for e_i||e_s||<0,0,1>. All the above peaks are reversible for temperature cycle. (3) Just after the cleavage a new peak appears at 126cm^<-1> and grows up above 250 K.This peak is irreversible. This peak originates from the precipitation of Te on the surface. Fresh cleaved surface is active for photo-induced atomic migration. For the model of chalcogen atom precipitation, an off-center self-trapped polaron mechanism is considered. The properties (2) and (3) indicate that the cleaved surface is chemically active.
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Report
(3 results)
Research Products
(5 results)
