Toyohiro Chikyow

Combinatorial methodology for optimizing oxide/semiconductor interface with atomic interfacial layers

A combinatorial methodology was employed to investigate oxide materials/semiconductor interfaces for future devices. For this purpose, a temperature gradient pulsed laser deposition to find optimum growth condition and transmission electron microscopy for structure and composition analysis were used. Newly proposed the micro sampling method with focused ion beam was applied to fabricate the specimen from the interested region in a shorter term. In growing oxide materials on Si substrate, a proper termination was found to be inevitable for avoiding surface oxidation. Arsenic was used to obtain a durable surface of Si in oxygen atmosphere. CeO 2 and SrTiO 3 were tried to grow and the interfaces were characterized using these method.

Combinatorial Approach to the Interface Structure Characterizations of SrTiO3 on Si(100)

Interface structures of SrTiO 3 /Si were investigated systematically using combinatorial method with growth temperature gradient in pulse laser deposition and cross sectional high resolution transmission electron microscopy . A combinatorial pulse laser deposition with growth temperature gradient system was employed to grow SrTiO 3 on Si (100) with various temperatures and oxygen pressures. A high throughput thin foil fabrication system, which is so called micro sampling system, was employed to fabricate thin foils for cross sectional high resolution transmission electron microscope observation. As a result, we have observed a never reported amorphized SrTiO 3 layer in the crystalline SrTiO 3 thin films grown on Si (100) at growth temperatures above 600°C. From the growth condition dependence studies on the formation of amorphized SrTiO 3 layers and the electron energy loss spectroscopy measurements, the origin of the amorphization was concluded as an effect of diffusion of Si from substrate. This is the first observation of a diffusion induced amorphization phenomenon in the crystalline SrTiO 3 thin films grown on Si (100). Our results show that at higher growth temperatures, the interface structures of SrTiO 3 /Si are dominated by the diffusion of Si from the Si substrates.