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| Titre : | Déposition des couches minces d'oxyde de zinc par spray pyrolysis : effet du dopage par l'indium et l'aluminium sur les propriétés physiques | | Type de document : | texte imprimé | | Auteurs : | BENOUIS EP.BENHALILIBA Chahrazade-eljamhoouria, Auteur | | Année de publication : | 2007 | | Importance : | 175 p | | Langues : | Anglais (eng) | | Catégories : | Physique:physique des semi conducteurs
| | Mots-clés : | d'oxyde de zinc,synthesized using ,temperture ,the physical , the microstructure | | Résumé : | ZnO thin were synthesozed using a simple method spray pyrolisis and an ultrat sonic spray method. The mean crystallite sizes and other structuran properties were estimated at various experimentale conditions using x-ray diffractiontechniques. The optical band gap and absorption coefficient were determined by optical measurement. The electrical resistivity and hall measurement gives the eletron concentration and the mobility. Also, we have studied the effet of illumination on the physical properties in the aim to have traps density and the engry traps.
The experimental conditions as substracte temperature a, time deposition has a strong effet on the physical properties. at low temperture and low time deposision, give an amorphous structure with a resistivity 227.cm. Increasing temperature, improve the resistivity and the optical transmittance by reducing the trap density. The trap energy above valence band is0.84 Ev which correspond to oxygen vacancy. We fixed the substrate temperature to 285C? TIME DEPOSISION TO 220s, we doped the films with the indium and Aluminium; in order to enhance the electrical conductivit2y in zno, the goals are to increase the carrier concentration and mobility simultaneously, Howerver, it is difficult to increase these two values simultaneously because these two values are interrelated with each other. The increase of carrier concentration can be achieved in two ways. The first second way is the introduction of extrinsic dopants such as trivalent atoms at zinc lattice sites and halogen atoms at oxygen lattice sites.
The mobility of carrier depends on the microstructnre such as grain boundary and other defects . the smaller grain sizes inducing the higher probability that the eletron will encounter ascattering event result in a decrease in mobility .
Nanocrystallzed ZnO obtained by UIra sonic spray were realized . the ZnO nanostructure grew in the direction (001) with improve in the optical band gap which shift to 3.42 eV the resistivity is then about 6.9 cm
Indium doping achieve the crystallinty , the band gap shift to4.2 eV the optical band gap of ZnO can shift by the introduction of intrinsic or extrinsic dopants this shift is called the Burstein –moss effect as the introduction of intrinsic or extrinsic dopants , this shift is called the Burstein –moss effect , as the carrier concentration increases , the Fermi energy moves above the conduction band edge which results from the complete occupation of states at the bottom of the conduction band therefore , optically stimulated transitions from valence band to these states can not occur and the optical band gap of ZnO increases the resistivity decrease to 0.01 cm
| | Directeur de thèse : | AIDA Mohamed salah |
Déposition des couches minces d'oxyde de zinc par spray pyrolysis : effet du dopage par l'indium et l'aluminium sur les propriétés physiques [texte imprimé] / BENOUIS EP.BENHALILIBA Chahrazade-eljamhoouria, Auteur . - 2007 . - 175 p. Langues : Anglais ( eng) | Catégories : | Physique:physique des semi conducteurs
| | Mots-clés : | d'oxyde de zinc,synthesized using ,temperture ,the physical , the microstructure | | Résumé : | ZnO thin were synthesozed using a simple method spray pyrolisis and an ultrat sonic spray method. The mean crystallite sizes and other structuran properties were estimated at various experimentale conditions using x-ray diffractiontechniques. The optical band gap and absorption coefficient were determined by optical measurement. The electrical resistivity and hall measurement gives the eletron concentration and the mobility. Also, we have studied the effet of illumination on the physical properties in the aim to have traps density and the engry traps.
The experimental conditions as substracte temperature a, time deposition has a strong effet on the physical properties. at low temperture and low time deposision, give an amorphous structure with a resistivity 227.cm. Increasing temperature, improve the resistivity and the optical transmittance by reducing the trap density. The trap energy above valence band is0.84 Ev which correspond to oxygen vacancy. We fixed the substrate temperature to 285C? TIME DEPOSISION TO 220s, we doped the films with the indium and Aluminium; in order to enhance the electrical conductivit2y in zno, the goals are to increase the carrier concentration and mobility simultaneously, Howerver, it is difficult to increase these two values simultaneously because these two values are interrelated with each other. The increase of carrier concentration can be achieved in two ways. The first second way is the introduction of extrinsic dopants such as trivalent atoms at zinc lattice sites and halogen atoms at oxygen lattice sites.
The mobility of carrier depends on the microstructnre such as grain boundary and other defects . the smaller grain sizes inducing the higher probability that the eletron will encounter ascattering event result in a decrease in mobility .
Nanocrystallzed ZnO obtained by UIra sonic spray were realized . the ZnO nanostructure grew in the direction (001) with improve in the optical band gap which shift to 3.42 eV the resistivity is then about 6.9 cm
Indium doping achieve the crystallinty , the band gap shift to4.2 eV the optical band gap of ZnO can shift by the introduction of intrinsic or extrinsic dopants this shift is called the Burstein –moss effect as the introduction of intrinsic or extrinsic dopants , this shift is called the Burstein –moss effect , as the carrier concentration increases , the Fermi energy moves above the conduction band edge which results from the complete occupation of states at the bottom of the conduction band therefore , optically stimulated transitions from valence band to these states can not occur and the optical band gap of ZnO increases the resistivity decrease to 0.01 cm
| | Directeur de thèse : | AIDA Mohamed salah |
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