1,721,023 research outputs found
DUAL-ION-BEAM SPUTTER DEPOSITION OF TIN FILMS
No full textA dual-ion-beam technique for the deposition of TiN thin films is described. The metal-atom flux is supplied by sputtering a titanium target with an inert ion beam, while the reactive flux is supplied directly to the growing film by a low-energy ion beam. Results are presented for titanium films deposited at room temperature under a range of N2+ ion bombardment to form TiN. Analysis gives the incorporation of nitrogen, the background gas contamination, and the optical and electrical properties of TiN films
DEEP LEVEL TRANSIENT SPECTROSCOPY OF MO GAAS SCHOTTKY BARRIERS PREPARED BY DC SPUTTERING
No full textDC sputtering of molybdenum allows the realization of near ideal Schottky barriers provided suitable deposition conditions are utilized. DLTS investigation shows that this kind of deposition process does not introduce damage defects if the sputtering voltage is below 2.5 kV, in our experimental conditions. The electrical characteristics get worse and a reduction in EL2 signal is evident for diodes prepared at the highest sputtering voltage. The reduction in EL2 signal is not an apparent effect related to the lowering of the barrier but it is strictly correlated to the damage due to the metal deposition process. A model, based on the outdiffusion of interstitial and antisite As, is proposed to interpret the experimental data
CHARACTERIZATION OF A DEFECT LAYER AT A SCHOTTKY-BARRIER INTERFACE BY CURRENT AND CAPACITANCE MEASUREMENTS
No full textThe electrical properties of a Ti/GaAs Schottky diode were investigated using electrical measurements under forward bias. The current, the low and high frequency capacitance and DLTS measurements evidence and describe in a consistent way the existence of a thin layer of defects induced by the metal deposition process near the interface. The quasi-saturation of the current and the excess low frequency capacitance are analysed by means of a generalization of a dipole layer model. The high density of states extending for several hundreds of Angstrom in the semiconductor is also evidenced by high frequency capacitance measurements. DLTS measurements using positive pulses confirm the presence of the traps and, together with the temperature analysis of the cut-off frequency, allow to study the trap emission process over a wide range of temperatures
TI/GAAS SCHOTTKY BARRIERS PREPARED BY ION-BEAM SPUTTERING
No full textSchottky barrier diodes of Ti on n-GaAs wafers were made by means of an ion beam sputtering (IBS) system under various sputtering conditions. We have investigated Schottky diode parameters by I-V and C-V measurements, and deep level centers by deep level transient spectroscopy (DLTS). The electrical characteristics are typical of good quality Ti/GaAs Schottky diodes for all samples, although a slight deterioration of the electrical performances has been observed for samples prepared at higher beam voltage. DLTS investigation shows the presence of damage defects in concentration lower than 1 x 10(14) cm-3 for all samples with the exception of those prepared at higher beam voltage. Such low concentration of defects introduced by the sputtering deposition shows that IBS can be a very useful technique to prepare Schottky barriers on GaAs
DETECTION OF COMBUSTIBLE GASES BY MEANS OF A ZNO-ON-SI SURFACE-ACOUSTIC-WAVE (SAW) DELAY-LINE
No full textZnO-on-Si surface acoustic wave (SAW) delay lines have been examined as detectors of some combustible gases (GO, NO, H-2), reactive gas such as O-2 and other gases (CH4, N-2, Ar). Measurements have been performed at temperatures of 20-160 degrees C, operation frequencies of 100-200 MHz and atmospheric pressure. The ZnO thin films have been prepared by reactive r.f. diode sputtering in an O-2/Ar atmosphere. The piezoelectric ZnO films deposited on the acoustic propagation path ensure both electromechanical transduction and gas detection. The relative changes of SAW phase velocity (acoustic response) upon absorption and desorption of a gas have been measured and compared with the change of electrical resistivity (electrical response) measured on the sensor in the same conditions. The effect of preliminary NO exposure on the acoustic responses for other gases is demonstrated. The time dependence of the acoustic response to NO is shown to be remarkably different from both its electrical response and from the acoustic responses to all other test gases. Therefore the shape of the time dependence can be used as a qualitative parameter for selective identification of NO. The relatively small interaction of Ar and N-2 with ZnO him makes them good carriers for other gases. Concerning the acoustic response, two possible processes of gas-molecule sorption by the ZnO film are briefly discussed
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