The electrical characteristics and the chemical composition profiles determined by XPS and SIMS for aluminum oxide thin films deposited by pulsed ultrasonic spray pyrolysis are reported. The films were deposited on c-Si at 550 ºC using a chemical solution of aluminum acetylacetonate as source of aluminum and N,NDimethylformamide as solvent, in addition a H 2 O-NH 4 OH mist was supplied simultaneously during deposition to improve the overall properties of these films. The results show that there is nitrogen incorporation in the films at the interface with the Si substrate. There is also a clear migration of silicon into the deposited film. The thickness of the films was in the range of 30 nm. Infrared spectroscopy also shows the presence of Si-O bonds. The dielectric constant for these films was higher than 8 and their interface trap density at midgap was in the 10 10 eV -1 cm -2 range.
Articles you may be interested inTwo dimensional electron transport in modulation-doped In0.53Ga0.47As/AlAs0.56Sb0.44 ultrathin quantum wells Correlation of the physical properties and the interface morphology of AlGaAs/GaAs heterostructures J. Appl. Phys. 94, 2464 (2003); 10.1063/1.1588360 Molecular beam epitaxial growth of normal and inverted two-dimensional electron gases in AlGaN/GaN based heterostructures J.We report a study of AlGaAs/GaAs semiconductor heterostructures with a two-dimensional electron gas system grown under different conditions by molecular beam epitaxy in three different laboratories. We performed photoreflectance ͑PR͒ measurements of this set of samples and analyzed the Franz-Keldysh oscillations associated with the E 0 transition of GaAs. We found that the sample with the highest electron mobility, as observed in Hall measurements at 77 K exhibited the lowest electric field strength. In addition, the 12 K photoluminescence ͑PL͒ spectra of the samples revealed intense and narrow free exciton luminescence in the sample with the highest electron mobility, while samples with lower mobility values showed impurities related PL lines. It is suggested that the electron mobility is affected by unintentional C impurities, which act like dispersion centers in the 2-DEG and increase the internal electric fields in the GaAs region. On the other hand, the PR spectra close to the AlGaAs band-gap energy region presented broad PR signals, due to the Si-doping in the alloy. The sample with the highest quality presented the most intense AlGaAs PR signal. We believe that low AlGaAs PR signal intensities are caused by unintentional incorporation of impurities during the preparation of the samples, which degrade the optical properties of the alloy.
The structural, optical and electrical properties of spray pyrolysis deposited lanthanum aluminum oxide are reported. The films were deposited from a spraying solutions of lanthanum nitrate and aluminum acetylacetonate in N, N- dimethylformamide using an ultrasonic generator on (100) Si substrates. The substrate temperature was in the 550-650°C range. The thickness was in below 300 Aå. The optical band gap was 5.3 eV, and the refractive index at 630 nm was up to 1.62 depending of the relation lanthanum-aluminum. The electrical characteristics of the films were determined from the capacitance and current versus voltage measurements of metal-oxide-semiconductor (MOS) structures incorporating them. A dielectric constant in the 6-12 range, interface states density of the order of 1012 X 1/eV cm2 as well as breakdown fields higher than 3 MV/cm were determine in this way.
The synthesis of La x Al 2-x O 3 films using ultrasonic spray pyrolysis technique are reported. The films were deposited from a spraying solution of aluminum acetylacetonate (Al(acac) 3 ) and lanthanum(III) nitrate hexahydrate La(NO 3 ) 3 6H 2 O dissolved in N,N-Dimethylformamide on (100) Si substrates. The substrate temperature during was in the range 500-600°C. The mean roughness was lower than 18 Å in all cases. The films were amorphous in all cases. The optical band gap was 5.42 eV and the refractive index was in the 1.64-1.72 range depending of the deposition conditions.
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