RESUMOBuscou-se a redução da tensão intrínseca causada pelas impurezas que se agregam no processo de crescimento de um filme de diamante obtido por deposição química a partir da fase vapor (CVD, do inglês Chemical Vapor Deposition) em um reator de filamento quente (HFCVD), sobre um substrato de silício <100> de 250 m de espessura em uma superfície de deposição de grande área (45 cm 2 ), através da imersão da amostra, em uma solução saturada de H 2 SO 4 e CrO 3 e, em seguida, em uma solução 1:1 de H 2 O 2 :NH 4 OH. Após esse procedimento, nova etapa de crescimento era realizada. O filme de diamante CVD foi identificado e caracterizado por espectroscopia de espalhamento Raman (RSS, do inglês Raman Scattering Spectroscopy) e microscopia eletrônica de varredura (SEM, do inglês Scanning Electron Microscopy). A aplicação dessa técnica mostrou bons resultados, uma vez que, em relação a resultados obtidos anteriormente, se duplicou a espessura do filme de diamante CVD depositado, obtendo menor tensão residual sobre o filme de diamante. Foram obtidos filmes de diamante CVD de espessura de 60 m, com alta qualidade e uniformidade. Palavras-chaves:Diamante CVD, crescimento, grandes áreas, filamento quente. CVD diamond films in large area obtained by successive steps of growth ABSTRACTThe aim of this work was the reduction of the intrinsic stress caused by the impurities added in the diamond film growth process by Chemical Vapor Deposition (CVD) in a hot filament reactor (HFCVD). Silicon <100> substrate of 250 m thickness with a deposition surface of great area (45 cm 2 ), was treated after each growth run through the immersion of the sample in a saturated solution of H 2 SO 4 and CrO 3 and, after that, in a H 2 O 2 :NH 4 OH solution 1:1. After this procedure, new stage of growth was carried through. The CVD diamond film was identified and characterized by Raman Scattering Spectroscopy (RSS) and Scanning Electron Microscopy (SEM). The application of this technique showed better results compared to previous one. The thickness of the deposited CVD diamond film doubled, obtaining lesser residual stress in the diamond film. CVD diamond films of 60 m thickness were obtained with high quality and uniformity.

Articles you may be interested inEffect of thermal annealing on optical emission properties of low-temperature grown AlGaAs/GaAs multiple quantum wells Structure and formation mechanisms of AlGaAs V-groove vertical quantum wells grown by low pressure organometallic chemical vapor deposition High quality Al(Ga)As/GaAs/Al(Ga)As quantum wells grown on (111)A GaAs substrates Resonant photorefractive AlGaAs/GaAs multiple quantum wells grown by molecular beam epitaxy at low temperature Standard molecular beam epitaxy is used to demonstrate the growth feasibility and reproducibility on the formation of microfacet array on the top surface of higher-index ͑311͒A quantum well structures. The quasiperiodic microfacet array was characterized by atomic force microscopy and was observed to be along the ͓233͔ direction, whereas for the ͑100͒ reference sample the microscopic surface morphology presented the terraces formation. We have used photoluminescence to characterize the optical properties of the samples. The observed redshift of the luminescence from the ͑311͒A sample, in relation to the ͑100͒ reference sample, was correlated with the existence of a lateral confinement potential induced by the period of faceting in this structure. The comparative analysis based on photoluminescence measurements have also shown the higher quality and the lower impurity incorporation for the ͑311͒A oriented samples.

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A direct comparative analysis is done in order to establish a clear correlation between magnetoresistance and photoluminescence measurements on the depopulation effect of higher energy electronic subbands induced by a planar magnetic field in Al 0.3 Ga 0.7 As/In 0.15 Ga 0.85 As/GaAs asymmetric quantum wells. The observed negative magnetoresistance and decreasing photoluminescence intensity with the magnetic field is in agreement with the reduction of the second subband electron density, which is obtained by a self-consistent calculation.

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