Person: Fernández Sánchez, Paloma
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First Name
Paloma
Last Name
Fernández Sánchez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Física de Materiales
Area
Ciencia de los Materiales e Ingeniería Metalúrgica
Identifiers
28 results
Search Results
Now showing 1 - 10 of 28
Item Cathodoluminescence study of laser recrystallized CdTe layers(Applied Physics Letters, 1997) Fernández Sánchez, Paloma; Piqueras de Noriega, Javier; Sochinskii, N. V.; Muñoz, V.; Bernardi, S.CdTe(100)/GaAs(100) and CdTe(lll)/CdTe(lll) layers grown by metalorganic vapor phase epitaxy (MOVPE) were investigated The layers were recrystallized to improve their morphology by scanning the surface with a 100 mu m diameter spot from an Ar ion laser beam (lambda=514.4 nm). Cathodoluminescence spectra from both as-grown and recrystallized CdTe MOVPE layers are used to monitor the effect of the recrystallization procedure. The laser recrystallization results in important changes on the spectral distribution of luminescence. Deep-level bands associated to different defects are shown to be very sensitive to the laser recrystallization procedure. The effect of the different substrates on the defect structure of the layers is also related to the changes observed in the cathodoluminescence spectra.Item Effect of ion beam milling on the defect structure of CdTe(Semiconductor Science and Technology, 1996) Panin, G. N.; Fernández Sánchez, Paloma; Piqueras de Noriega, JavierThe effect of ion milling on the defect structure of CdTe crystals has been investigated in the scanning electron microscope by cathodoluminescence. Enhancement in the luminescence intensity is observed after ion treatment. Luminescence spectra of treated and untreated zones of the samples indicate that ion milling causes generation of tellurium vacancies and filling of cadmium vacancies in a subsurface layer. In addition, enhancement of the concentration of cadmium vacancy related defects in the region extending up to 20 mu m from the layer is revealed. This effect is discussed in connection with models of p- to n-type conversion of CdTe during ion milling.Item Study of electronic deep levels in CdTe and CdTe:V by cathodoluminescence microscopy(Electron Microscopy 1994, Vols 2a and 2b: Applications in Materials Sciences, 1994) Pal, U.; Piqueras de Noriega, Javier; Fernández Sánchez, Paloma; Serrano, M. D.; Diéguez, E.Item Deep energy levels in CdTe and CdZnTe(Journal of Applied Physics, 1998) Castaldini, A.; Cavallini, A.; Fraboni, B; Fernández Sánchez, Paloma; Piqueras de Noriega, JavierThe deep levels present in semiconducting CdTe and semi-insulating CdTe:Cl and Cd0.8Zn0.2Te have been investigated by means of cathodoluminescence, deep level transient spectroscopy (DLTS), photo-induced current transient spectroscopy, and photo-DLTS. The latter two methods, which can be applied to semi-insulating materials, allow to characterize the deep traps located up to midgap and can determine whether they are hole or electron traps. We have identified 12 different traps, some common to all the investigated samples, some peculiar to one of them. A comparison of the results obtained from the various materials is given and the status of defect models is reviewed.Item Luminescence from growth topographic features in GaN : Si films(Journal of Applied Physics, 1998) Zaldivar, M.H.; Fernández Sánchez, Paloma; Piqueras de Noriega, JavierCathodoluminescence (CL) in the scanning electron microscope is used to investigate the nature of defects responsible for the luminescence associated with round and hexagonal-like topographic features of GaN:Si films. Round hillocks of the size of a few microns, which sometimes have a nanopipe related central hole, do not influence the luminescence emission of the film. Hillocks with sizes of several tens of microns show a marked CL contrast at the center and at the border. The origin of the observed contrast is attributed to a growth induced inhomogeneous distribution of point defects and impurities. Radiation with the electron beam of the scanning microscope causes a decrease of the CL intensity without spectral changes.Item Deep-level cathodoluminescence in deformed CdTe crystals(Physica Status Solidi A-Applied Research, 1995) Díaz-Guerra Viejo, Carlos; Pal, U.; Fernández Sánchez, Paloma; Piqueras de Noriega, JavierThe effect of indentation on the cathodoluminescence (CL) of CdTe in the scanning electron microscope is investigated. Deformation produces deep level emission changes, in particular, a relative intensity increase of the 1.4 and 1.1 eV bands, explained by vacancy generation. Deep level centers are not found to be related to the CL image contrast changes caused by annealing.Item Luminescence from Bi_2Sr_2CaCu_2O_x and YBa_2Cu_3O_(7-x) films in the scanning electron-microscope(Journal of Applied Physics, 1992) Domínguez-Adame Acosta, Francisco; Fernández Sánchez, Paloma; Piqueras de Noriega, Javier; Prieto, P.Visible and near infrared cathodoluminescence of Bi_2Sr_2CaCu_2O_x and YBa_2Cu_3O_(7-x) films is investigated in the scanning electron microscope. In particular, possible analogies in the cathodoluminescence of both systems have been analyzed. The spectra show only minor and slightly defined common features. Low-temperature observations show the capability of the cathodoluminescence technique to detect fine structural transitions. Some transformations induced by the electron beam are described.Item Cross-sectional cathodoluminescence of GaN epitaxial films(Nitride semiconductors, 1998) Zaldivar, M.H.; Fernández Sánchez, Paloma; Piqueras de Noriega, JavierCathodoluminescence (CL) in the scanning electron microscope has been used to investigate the variation along the growth axis direction of luminescence emission from epitaxial GaN films. CL spectra recorded at different positions of the sample cross-section as well as monochromatic CL images show strong spatial variations of the different luminescence emissions along the growth axis. At the buffer layer-substrate interface and at the top part of the sample, which corresponds to a Si doped epilayer, enhanced CL emission is observed as compared with the relatively low emission in the central region of the cross-section. The nature of the defects responsible for the observed CL distribution is discussed.Item Influence of deformation on the luminescence of GaN epitaxial films(Semiconductor Science and Technology, 1998) Zaldivar, M.H.; Fernández Sánchez, Paloma; Piqueras de Noriega, JavierThe effect of indentation on the cathodoluminescence (CL) of GaN:Si epitaxial films has been investigated in the scanning electron microscope. Deformation produces changes in the defect structure which are monitored through the changes induced in the cathodoluminescent emission. Besides a general quenching of the luminescence, an increase of the relative intensity of the deep level bands is observed. The effect of different annealing treatments on the CL emission has been investigated.Item Cathodoluminescence microscopy and photoluminescence of defects in ZnTe(Semiconductor Science and Technology, 1998) Fernández Sánchez, Paloma; García, J. A.; Remon, A; Piqueras de Noriega, Javier; Muñoz, V.; Triboulet, R.ZnTe single crystals grown by the cold travelling heater method have been investigated by means of photo-and cathodoluminescence. The spectral region covered in this work ranges from 2.48 eV (500 nm) which corresponds to band-edge emission to 0.62 eV (2000 nm). Visible and infrared cathodoluminescence images have been recorded, and the influence of extended defects on the observed luminescence has been studied.
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