Summary
Absorption and electroabsorption (EA) measurements allow a description of the valence and conduction bands of SrTiO3, in theΔ-direction. This type of information has been obtained from the analysis of structure in the absorption tail, which is observed in the low-temperature spectra. Urbach’s behavior appears above 160 °K and is experimentally followed up to 514 °K. Possible mechanisms for the evolution of the absorption tail with temperature are discussed.
Riassunto
Misure di assorbimento e di elettroassorbimento (EA) permettono di descrivere l’andamento delle bande di conduzione e di valenza di SrTiO3, nella direzioneΔ. Questo tipo di informazioni è stato dedotto dall’analisi delle strutture che, a basse temperature, si osservano nella coda di assorbimento. Al di sopra di 160 °K, gli spettri mostrano un comportamento urbachiano che si segue sperimentalmente fino a 514 °K. Si discutono i possibili meccanismi responsabili dell’evoluzione della coda di assorbimento con la temperatura.
Резюме
Измерения по поглоще нию и электропоглоще нию позволяют описат ь валентную зону и зону проводимости д ля SrTiO3, вΔ -направлении. Э та информация была получена на осно ве анализа структуры хвоста поглощения, ко торый наблюдается в спектрах при низких температурах. Поведе ние Урбаха возникает при температуре выше 160 °K и эксперимент ально прослеживаетс я вплоть до 514 °K. Обсужда ются возможные механизмы для эволюции хвоста п оглощения с температ урой.
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References
A. H. Kahn andA. J. Leyendecker:Phys. Rev.,135, A 1321 (1964).
C. S. Koonce, M. L. Cohen, J. F. Schooley, W. E. Hosler andE. R. Pfeiffer:Phys. Rev.,163, 380 (1967).
H. P. R. Frederikse:Electronic Structure in Solids (New York, 1969), p. 259, and references therein.
Z. Sroubek:Sol. State Comm.,7, 1561 (1969);Phys. Bev. B,2, 3170 (1970).
M. Cardona:Phys. Rev.,140, A 651 (1965).
A. Frova andP. J. Boddy:Phys. Rev.,153, 606 (1967).
F. Urbach:Phys. Rev.,92, 1324 (1953).
M. Capizzi andA. Frova:Phys. Rev. Lett.,25, 1298 (1970).
A. Frova andP. Handler:Phys. Rev. 137, A 1857 (1965).
E. A. Forman, D. E. Aspnes andM. Cardona:Journ. Phys. Chem. Solids,31, 227 (1970).
Previous experiments in SrTiO3 (M. I. Cohen andR. F. Blunt:Phys. Rev.,168, 929 (1968)) revealed no structure. High-energy saturation was seen byD. Redfield andW. Burke:Bull. Am. Phys. Soc.,15, 394 (1970), and for KTaO3 in ref. (12). Structure in SrTiO3 has previously been observed in photoconductivity (A. K. Ghosh:Sol. State Comm.,7, paper 2–5 (1969); for this see also ref. (13).
A. Frova:Nuovo Cimento,55 B, 1 (1968).
L. Grabner:Phys. Rev.,177, 1315 (1969).
S. H. Wemple: to be published.
F. W. Lytle:Journ. Appl. Phys.,35, 2212 (1964).
K. A. Müller, W. Berlinger, M. Capizzi andH. GrÄnicher:Sol. State Comm.,8, 549 (1970).
J. R. Brews:Phys. Rev. Lett.,18, 662 (1967).
R. C. Casella:Phys. Rev.,154, 743 (1967).
C. GÄhwiller:Helv. Phys. Acta,38, 361 (1965).
M. Di Domenico jr. andS. H. Wemple:Phys. Rev.,166, 565 (1968).
J. D. Zook andT. N. Casselman:Phys. Rev. Lett.,17, 960 (1966).
M. Di Domenico jr. andS. H. Wemple:Journ. Appl. Phys.,40, 720 (1969).
J. F. Nye:Physical Properties of Crystals (London, 1957), p. 114.
W. G. Nilsen andS. G. Skinner:Journ. Chem. Phys.,48, 2240 (1968).
F. S. Chen, J. E. Geusic, S. K. Kurtz, J. C. Skinner andS. H. Wemple:Journ. Appl. Phys.,37, 388 (1966).
Y. Fujii andT. Sakudo:Journ. Appl. Phys.,41, 4118 (1969).
S. H. Wemple, M. Di Domenico jr. andI. Camlibel:Appl. Phys. Lett.,12, 209 (1968).
H. Unoki andT. Sakudo:Journ. Phys. Soc. Japan,23, 546 (1967).
P. A. Fleury, J. F. Scott andJ. M. Worlock:Phys. Rev. Lett.,21, 16 (1968).
H. Thomas andK. A. Müller:Phys. Rev. Lett.,21, 1256 (1968).
J. M. Worlock : private communication.
A. Feldman andD. Horowitz:Sol. State Comm.,6, 607 (1968).
R. F. Schaufele andM. J. Weber:Journ. Chem. Phys.,46, 2859 (1967).
A. S. Barker jr.:Phys. Rev.,145, 391 (1966), and references therein.
S. Shapiro:Phys. Rev.,140, A 169 (1965).
W. P. Dumke:Phys. Rev.,108, 1419 (1957).
D. Dunn:Phys. Rev.,174, 855 (1968).
B. L. Joesten andF. C. Brown:Phys. Rev.,148, 919 (1966).
E. A. Cowley:Phys. Rev.,134, A 981 (1964).
A. Frova andP. Migliorato: unpublished data; see also Cohen and Blunt in ref. (11).
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Capizzi, M., Frova, A. Determination of the nature of the optical gap of SrTiO3 . Il Nuovo Cimento B (1971-1996) 5, 181–203 (1971). https://doi.org/10.1007/BF02738147
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DOI: https://doi.org/10.1007/BF02738147