CaracterizaÃÃo de filmes de CdS preparados pela tÃcnica de deposiÃÃo por laser pulsado (PLD)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

In this work, we have designed and installed a system for thin films deposition using a Nd:YAG laser as the source of energy for evaporation. The technique is known as: Pulsed Laser Deposition, PLD. The excitation wavelengths used were 1064 nm and 532 nm. The target was a pressed powder tablet of CdS. Characterization of the films was performed using X-rays Diffraction (XRD), Electron Microscopy, optical transmission, photoluminescence, and far and medium infrared absorption by Fourier Transform Spectroscopy. The films obtained have crystalline wurtzite structure with the c axis highly oriented in the perpendicular direction to the substrate surface. As far as we know, this is an original result for films prepared with 532 nm excitation. Using the optical transmission and absorption spectra it was possible to obtain important parameters such as: the films thicknesses, refraction index, optical gap, and relative impurity concentration. It was observed a decrease of the impurity concentration by surplus of Cd with the increasing of the laser fluence and the decreasing of the evaporation wavelength. The increasing of the laser fluence also induced a decreasing of the optical gap of material due to the creation of inside gap levels of the impurities and defects. Impurity bands were studied by far and medium infrared absorption by Fourier Transform Spectroscopy. Characteristic photoluminescence spectra were obtained in the green region. The optical result provided strong evidence of the high quality of the CdS films produced

ASSUNTO(S)

laser ablation thin solid film fisica pld

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