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We report a complete characterization of InAsxP1-x/InP (0.05<x<0.,59) superlattices epitaxially grown by low pressure metalorganic chemical vapor deposition and by chemical beam epitaxy, Samples were obtained by both conventional growth procedures and by periodically exposing the just-grown InP surface to an AsH3 flux. Using the latter procedure, very thin InAsxP1-x/InP layers (10-20 Angstrom) are obtained by P<->As substitutions effects, Arsenic composition of the so obtained layers depends both on AsH3 flux intensity and exposure times, Samples have been characterized by means of high resolution x-ray diffraction, high resolution transmission electron microscopy, 3 IC photoluminescence, and extended x ray absorption fine structure spectroscopy, The combined use of high resolution x-ray diffraction and of 4 K photoluminescence, with related simulations, allows us to predict both InAsP composition and width, which are qualitatively confirmed by electron microscopy. Our study indicates that the effect of the formation of thin InAsP layers is due to the as incorporation onto the InP surface exposed to the As flux during the AsH3 exposure, rather than the residual As pressure in the growth chamber during InP growth, Arsenic K-edge extended x-ray absorption fine structure analysis shows that the first shell environment of As at these interfaces is similar to that found in bulk InAsxP1-x, alloys of similar composition, In particular we measure an almost constant As-in bond length (within 0.02 Angstrom), independent of As concentration; this confirms that epitaxy with InP is accompanied by local structural distortions, such as bond angle variations, which accommodate the nearly constant As-In bond length. In our investigation we characterize not only very high quality heterostructures but also samples showing serious inter-face problems such as nonplanarity and/or a consistent chemical spread along the growth axis, In the study presented here we thus propose a general method, based on several independent techniques, for the characterization of the interface quality of semiconductor superlattices.
Structural and optical investigation of InAsxP1-x/InP Superlattices
We report a complete characterization of InAsxP1-x/InP (0.05As substitutions effects, Arsenic composition of the so obtained layers depends both on AsH3 flux intensity and exposure times, Samples have been characterized by means of high resolution x-ray diffraction, high resolution transmission electron microscopy, 3 IC photoluminescence, and extended x ray absorption fine structure spectroscopy, The combined use of high resolution x-ray diffraction and of 4 K photoluminescence, with related simulations, allows us to predict both InAsP composition and width, which are qualitatively confirmed by electron microscopy. Our study indicates that the effect of the formation of thin InAsP layers is due to the as incorporation onto the InP surface exposed to the As flux during the AsH3 exposure, rather than the residual As pressure in the growth chamber during InP growth, Arsenic K-edge extended x-ray absorption fine structure analysis shows that the first shell environment of As at these interfaces is similar to that found in bulk InAsxP1-x, alloys of similar composition, In particular we measure an almost constant As-in bond length (within 0.02 Angstrom), independent of As concentration; this confirms that epitaxy with InP is accompanied by local structural distortions, such as bond angle variations, which accommodate the nearly constant As-In bond length. In our investigation we characterize not only very high quality heterostructures but also samples showing serious inter-face problems such as nonplanarity and/or a consistent chemical spread along the growth axis, In the study presented here we thus propose a general method, based on several independent techniques, for the characterization of the interface quality of semiconductor superlattices.
C. Lamberti; S. Bordiga; F. Boscherini; S. Mobilio; S. Pascarelli; L. Gastaldi; M. Madella; C. Papuzza; C. Rigo; D. Soldani; C. Ferrari; L. Lazzarini; G. Salviati
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/111207
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Il report seguente simula gli indicatori relativi alla produzione scientifica in relazione alle soglie ASN 2023-2025 del proprio SC/SSD. Si ricorda che il superamento dei valori soglia (almeno 2 su 3) è requisito necessario ma non sufficiente al conseguimento dell'abilitazione.
La simulazione si basa sui dati IRIS e presenta gli indicatori calcolati alla data indicata sul report. Si ricorda che in sede di domanda ASN presso il MIUR gli indicatori saranno invece calcolati a partire dal 1° gennaio rispettivamente del quinto/decimo/quindicesimo anno precedente la scadenza del quadrimestre di presentazione della domanda (art 2 del DM 598/2018).
In questa simulazione pertanto il valore degli indicatori potrà differire da quello conteggiato all’atto della domanda ASN effettuata presso il MIUR a seguito di:
Correzioni imputabili a eventuali periodi di congedo obbligatorio, che in sede di domanda ASN danno diritto a incrementi percentuali dei valori.
Presenza di eventuali errori di catalogazione e/o dati mancanti in IRIS
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