The properties of Pt-diffused MOS structures are experimentally investigated. It is pointed out that Pt-diffusion ambient and crystal orientation of the wafers have direct effect upon the large shift effect of flatband voltage or the nonvolatile memory properties. The mechanism of the electrical behavior at Si-SiO2 interface on Pt-diffused MOS devices is discussed. Moreover, The n-channel enhancement MOSFET with the large positive shift of flatband voltage is fabricated, and the effective mobility and Vth are evaluated. Again, the MOS device with nonvolatile memory effect is fabricated, and the properties of erasing and writing time are investigated.
GaP/Chl-a/Au and GaP/Cu-Pc/Ag cells were constructed from nor ptype GaP wafers, chlorophyll-a (Chl-a) or Cu-phthalocyanine (Cu-Pc) and evaporated metal films. The n-GaP/ Chl-a/Au cell exhibited strong rectification in the dark and photovoltaic effect on steady state illumination, whereas the effects for the p-GaP/Chl-a/Au cell were weak. Since Chl-a is a p-type semiconductor, a hetero pn junction exists at the n-GaP/Chl-a interface. The GaP/Cu-Pc/Ag cells exhibited rectification in the dark due to heterojunctions at the GaP/ Cu-Pc interface, and photovoltaic effects due to both the heterojunctions and Schottky junc-tions at the Cu-Pc/Ag interfaces. The power conversion efficiency of the cells was 0.1% at its maximum.
Ta2O5 thin films have recently been applied in integrated optical devices and as antire-flection coatings on solar cells. These applications are essentially based on the high chemical stability of the film and especially on its optical properties such as a very low propagation loss for light. But all these films are amorphous. In this work, we deposited Ta2O5 on a quartz substrate by the reactive DC diode sputtering of a tantalum target in a mixture of argon plus oxygen for the purpose of getting a crystallizedfilm. It was proved through the study that oriented Ta2O5 thin films and amorphous Ta2O5 thin films are easily deposited independently according to the sputtering conditions. We report here the first observation of piezoelectric phenomena in oriented Ta2O5 thin films. We have succeeded in exciting surface acoustic waves on the Ta2O5 thin film by the inter-digital transducer.