title: Characterization of Pb₂₄Te₇₆ quantum dot thin film synthesized by inert gas condensation.
abstract: Air-stable and thermal-stable lead telluride quantum dot was successfully prepared on glass substrate by inert gas condensation (IGC) method. Argon (Ar) is the inert gas used during deposition process with a constant flow rate of 3 × 10(-3)Torr. The effect of heat-treatment process at different times was studies for structure, optical and electrical properties for nanocrystalline thin films. The structures of the as deposited and heat-treated films were investigated using grazing incident in-plane X-ray diffraction (GIIXD). The GIIXD pattern showed nanostructure face centered cubic structure of PbTe thin films. The energy dispersive X-ray analysis (EDX) of as deposited PbTe thin film was carried out and showed that the atomic ratio of Pb/Te was 24/76. The particle size of the as deposited PbTe film and after stored it in an unhumid atmosphere are 6.8 ± 0.3 nm and 7.2 ± 0.3 nm respectively as estimated form TEM image (i.e. in the same level of particle size). However, the particle size was changed to be 11.8 ± 0.3 nm after heat-treated for 5h at 473K. These particle size values of PbTe thin film are smaller than its Bohr radius. The estimated value of optical band gap Eg decreased from 1.71 eV for the as deposited film to 1.62 eV for film heat-treated (5 h at 473K). The dc electrical conductivity is increased with raising temperature in the range (303-473K) for all thin films under investigation. The deduced activation energy decreased from 0.222 eV for as deposited sample to 0.125 eV after heat-treated at 473K for 5 h.
authors.affiliation: Solid State Physics Department, National Research Center, 12622 Dokki, Cairo, Egypt. Electronic address: mams411@gmail.com.
authors.forename: Manal A
authors.initials: MA
authors.lastname: Mahdy
authors.affiliation: Department of Physics, Faculty of Science (Girls), Al-Azhar University, 11753 Nasr City, Cairo, Egypt.
authors.forename: Iman A
authors.initials: IA
authors.lastname: Mahdy
authors.affiliation: Solid State Physics Department, National Research Center, 12622 Dokki, Cairo, Egypt.
authors.forename: I K
authors.initials: IK
authors.lastname: El Zawawi
mesh_terms: D003460:Crystallization / Q000379:methods; D004553:Electric Conductivity; D006358:Hot Temperature; D007854:Lead / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D045663:Quantum Dots / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D007854:Lead; D013691:Tellurium
keywords: Air-stable and thermal-stable lead telluride thin films; Electrical properties; Heat-treatment; Inert gas condensation; Nanostructure; Optical properties