0000000000948645
AUTHOR
Mauricio Morais De Lima
Influence of krypton atoms on the structure of amorphous hydrogenated carbon deposited by plasma enhanced chemical vapor deposition
Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH4 ) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectrosco…
Embedded interdigital transducers for high frequency surface acoustic waves on GaAs
We investigate high-performance, high-frequency interdigital transducers (IDTs) for the generation of surface acoustic waves(SAWs) on GaAs substrates, where the metal fingers are embedded in the substrate. We demonstrate that the acoustic reflections and the scattering of the surface modes into the substrate become considerably reduced in these transducers, leading to an increased output power. The finger embedding process is particularly relevant for the generation of powerful beams of high-frequency SAWs on weak piezoelectric substrates (such as most of the semiconducting materials) using long IDTs. We also show that the reflection reduction is important for the design of focusing single-finge…
Light induced electron spin resonance in a-Ge:H
We report the observation of light-induced electron spin resonance (LESR) in amorphous hydrogenated germanium. Two new lines with zero crossings near g=2.01 and g=2.03 were detected and ascribed to electrons and holes in the conduction- and valence-band-tail states, respectively. The ratio between the LESR spin densities of both lines is approximately one, suggesting the absence of spin pairing, charge defect creation, or LESR of dangling bonds. The growth and decay spectra exhibit dispersive behavior with a dispersion parameter ∼0.5. The decay spectrum is best fit assuming bimolecular recombination. The LESR spin density depends weakly on the photogeneration rate as a sublinear power law.