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Photoluminescence and electrical study of fluctuating potentials in Cu2ZnSnS4-b...
Leitão, J. P.; Santos, N. M.; Fernandes, P. A.; Salomé, P. M. P.; Cunha, A. F. da; González, J. C.; Ribeiro, G. M.; Matinaga, F. M.In this work, we investigated structural, morphological, electrical, and optical properties from a set of Cu2ZnSnS4 thin films grown by sulfurization of metallic precursors deposited on soda lime glass substrates coated with or without molybdenum. X-ray diffraction and Raman spectroscopy measurements revealed the formation of single-phase Cu2ZnSnS4 thin films. A good crystallinity and grain compactness of the f...
Low frequency oscillations and bifurcation diagram in semi-insulating GaAs samples
Silva,R. L. da; Albuquerque,H. A.; Rubinger,R. M.; Oliveira,A. G. de; Ribeiro,G. M.; Rodrigues,W. N.We present an experimental study of bifurcation diagrams from low frequency current oscillations (LFO) measurements obtained from semi-insulating GaAs samples grown by low temperature molecular beam Epitaxy (LT-MBE). The considered growth temperatures were 215ºC and 265ºC. LFO are considered to be spontaneously generated oscillations under constant applied bias V. These oscillations were measurement and recorde...
Variable range hopping conduction in low-temperature molecular beam epitaxy GaAs
Rubinger,R. M.; Albuquerque,H. A.; Silva,R. L. da; Oliveira,A. G. de; Ribeiro,G. M.; Rodrigues,W. N.; Rubinger,C. P. L; Moreira,M. V. B.Electric transport properties measured by Van der Pauw resistivity experiments of Low-Temperature Molecular Beam Epitaxy (LT-MBE) GaAs samples are used to identify a method to improve the resistivity of GaAs material. We present results on five samples grown at 265, 310, 315, 325, and 345 ºC. The electric measurements were carried out at temperatures ranging from 130 to 300 K. In this temperature range the domi...
Modeling chaotic current oscillations in semi-insulating GaAs with rate-equatio...
Albuquerque,H. A.; Silva,R. L. da; Rubinger,R. M.; Oliveira,A. G. de; Ribeiro,G. M.; Rodrigues,W. N.We investigated the effect of adding the field-dependent recombination process, namely field-enhanced trapping, to the generation-recombination processes of charge carriers that model current oscillations in semiconductors. The main new features arising from this modification are identified in bifurcation diagrams with the electric field as the control parameter. The characteristic of the bifurcation diagrams i...
Hall effect in InAs/GaAs superlattices with quantum dots: identifying the prese...
Rubinger,R.M.; Ribeiro,G.M.; Oliveira,A.G. de; Albuquerque,H.A.; Silva,R.L. da; Rodrigues,W.N.; Moreira,M.V.B.We have carried out van der Pauw resistivity and Hall effect measurements on a series of Molecular Beam Epitaxy InAs/GaAs superlattice samples containing InAs quantum dots. Three growth parameters were varied, the InAs coverage, the number of repetitions of the InAs/GaAs layers, and the GaAs spacer thickness. The results can be grouped in two sets, those samples presenting low and high resistivity. The group pr...
Nonlinear dynamics time series analysis of chaotic current oscillations in a se...
Silva,R.L. da; Rubinger,R.M.; Oliveira,A.G. de; Ribeiro,G.M.We have carried out our experiments on a semi-insulating GaAs sample grown by low temperature Molecular Beam Epitaxy. Three parameters were used to fine tune the experiments, namely, temperature, illumination, and applied bias. We have used powerful tools of time series analysis in order to assess the embedding dimension through near false nearest neighbors. We have also measured the maximum Lyapunov exponent a...
Observation of low frequency oscillations in GaAs samples grown by molecular be...
Rubinger,R. M.; Oliveira,A. G. de; Ribeiro,G. M.; Soares,D. A. W.; Moreira,M. V. B.We have observed Low Frequency Oscillations (LFO) in a GaAs sample grown by molecular beam epitaxy (MBE) at 300 °C as a function of applied electric field, temperature and illumination intensity. Time series of the oscillations for different values of the applied electric field at room temperature were obtained. We have also obtained the jxE characteristics as a function of temperature and light intensity. We w...
Impurity breakdown in GaAs samples grown by molecular beam Epitaxy
Rubinger,R.M.; Oliveira,A.G. de; Ribeiro,G.M.; Bezerra,J.C.; Silva,C.M.; Rodrigues,W.N.; Moreira,M.V.B.In this work we present studies for the behavior of impurity breakdown of two GaAs samples grown by Molecular Beam Epitaxy at 200°C and 300°C. We vary the temperature and the illumination intensity. For the sample grown at 200°C, the transport mechanism after the breakdown is of the same type of the main free carriers at low electric fields. Below 100K, a clear dependence of the threshold electric field with te...
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