Satoru Morita

Tunneling Current through Ultrathin Silicon Dioxide Films under Light Exposure

Tunneling current through ultrathin silicon dioxide films with a thickness of approximately 3.1 nm, formed on n-Si (100) by controlling preoxide growth during heating, is examined using Al/oxide/n-Si structures. Electron tunneling current through the oxide from n-Si to Al is decreased and the dielectric breakdown voltage is increased by the preoxide growth control. Electron tunneling current from Al to n-Si is increased by light exposure. The increase in electron tunneling current can be explained by the increase in oxide voltage with an inversion layer formed by photoexcitation.

Reaction of Hydrogen-Desorbed Si(100) Surfaces with Water during Heating and Cooling

The reaction of hydrogen-terminated Si(100) surfaces with water during heating is analyzed using a combination of heating and cooling in thermal desorption spectroscopy. The reaction of the Si surface with water after hydrogen desorption is observed even at about 400°C at a low concentration of water molecules. An estimation method of surface hydrogen coverage by the combined measurement is proposed and the surface coverage as a function of temperature is estimated for quantitative understanding of hydrogen desorption and the subsequent reaction during heating. The combined measurement in thermal desorption spectroscopy is useful for revealing the reaction after hydrogen desorption during heating and for estimating the surface coverage.

Photodetector Characteristics of Metal-Oxide-Semiconductor Tunneling Structures with Transparent Conductive Tin Oxide Gate

The integration of optics on a silicon (Si) substrate through metal-oxide-semiconductor (MOS) compatible processes is becoming important for optical interconnects, image sensors or monolithic optical biosensors [1]. The MOS tunneling structure has used as a photodetector [2]. However, the indium tin oxide sputtering process has been reported to degrade photodetector performance. In this study, we have examined the photodetector characteristics of MOS diodes with tin oxide (SnO2)/ultrathin silicon dioxide (SiO2)/n-Si structures.

Reaction of Hydrogen-Terminated Si(100) Surfaces with Oxygen at Very Low Pressures during Heating

Reactions of hydrogen-terminated Si(100) surfaces with oxygen at very low pressures during heating are characterized by a method that combines heating and cooling in thermal desorption spectroscopy. Surface hydrogen coverage as a function of temperature is estimated from the hydrogen desorption spectrum obtained by the combination measurement. The surface coverage under the condition with or without introducing oxygen gas indicates that the hydrogen of silicon monohydride begins to desorb after almost half the hydrogen of silicon dihydride desorbs. The hydrogen desorption behavior under the introduction of oxygen gas suggests that bonding between Si and hydrogen atoms for silicon monohydride at the Si(100) surface is stabilized by adsorption of oxygen atoms on surface Si back bond sites during heating.

Energy barrier heights of ultra-thin silicon dioxide films with different metal gates

In this study, we have examined a way to determine the barrier height of ultra-thin SiO/sub 2/ films by current density-oxide voltage characteristics of MOS diode using different metal gates.

Tunneling current through ultra-thin silicon dioxide films formed by controlling preoxide in heating-up

With the down-scaling of metal-oxide-semiconductor field effect transistors (MOSFETs), the gate oxide thickness becomes extremely thin. Ultrathin silicon dioxide films with high electric insulating performance and high reliability are demanded in order to realize ultra-small MOSFETs for large scale integration (LSI) chips. The influence of a preoxide grown during silicon wafer heating up to thermal oxidation temperature on the dielectric performance cannot be neglected as the gate oxide becomes thin. Thick preoxides in ultrathin gate oxide films can induce degradation of the electric insulating performance. In this study, we have investigated the influence of the preoxide on the dielectric characteristics and have examined the characteristics of silicon dioxide films with thicknesses of 1-3 nm.