Basic research on selective epitaxy in very limited areas

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We present a new fabrication process of Si epitaxial nanostructures on A12O3 by electron beam irradiation. We found that an A12O3 surface was modification was caused by desorption of wxygen atoms from the surface by electron beam irradiation and research on selective epitaxial growth using this phenomenon are being conducted. We confirmed that Si films were selectively grown on non-electron-beam irradiated areas of (0112) and (0001) alpha-A12O3 substrates and (100) gamma-A12O3 on (100) Si substrates by Si2H6 gas-source MBE with growth temperatures ranging from 700ﾟC to 900ﾟC.This method consists mainly of following two procedure ; electron beam irradiation on the A12O3 surface, and then Si growth with Si2H6 gas source molecular beam epitaxy (MBE). After these processes, Si nanostructures are selectively fabricated on A12O3. si nanostructures could be grown on only non-irradiated electron beam areas. Because this method does not require oxide masks that are used in conventional selectiv … More e epitaxy, it might be possible to achieve further micro miniaturization. Si selective growth mechanism is based on desorption of oxygen atoms from A12O3 surface and transformation of the surface changes from A12O3 to metal-like Al.A new fabrication method of Si mesoscopic structures on A12O3 by selective epitaxial growth using an electron beam irradiation was investigated. From observation with atomic force microscope (AFM) and scanning electron microscope (SEM), Si dots of 250nm diameter and 30nm height were obtained. It was confirmed that those positions and size were uniformly controlled. Si wires of 250nm width and 30nm height were uniformly formed on the sapphire and Si nucleus was hardly existed on the amorphous Al oxide areas. we found that position and size controlled Si mesoscopic structures were formed on a sapphire substrate. The shapes of the Si mesoscopic structures by this method depend greatly on the electron beam dose density.High-crystalline quality A12O3 films on Si for SOI structures were also investigated using solid source Al and N2O gas source MBE instead of TMA to reduce carbon contamination. Selective etching method of A12O3 single crystalline films were developed using Si ion implantation method. This method could become useful to SOI devices. Less