Preparation and Characterization of Si-based Manmade Crystals

点击翻译按钮获取中文摘要

Growth characteristics have been investigated in detail for atomic-layr epitaxy (ALE) of Si on the (111) surface by using SiH2Cl2 and atomic H.Gas-phase-generation of SiHCl radials by collision plays a very important role for an ideal one monolayr per cycle growth rate, and there are proper gas pressure and residence time for dense generation of SiHCl radials. For (100) surface, atomic H can etch the SiCl molecule chemisorbed on the surface, and this hydrogen pressure should be kept low. Based on these results, a wide ALE temperature window has been achieved for both (100) and (111) surfaces.Ge-ALE has been achieved by using GeH2(CH3)2 and H for the (100) and (111) surfaces. The ALE temperature window for the (111) surface was as narrow as 20oC while it was as wide as 100oC for the (100) surface. Origin of this narrow window was attributed to the Modified Ealy-Redeal mechanism for the atomic H induced subtraction of methyl groups from the Ge-methyl dond.Monolayr adsorption of Si has been achieved on the Ge surface by using SiH4 gas. Digital growth with an ideal one-monolayr step was achieved by successive Si-ALE on the Ge surfase adsorbed by Si. Interface abruptness has been evaluated by AES and SIMS and it was confirmed that the transition layr was as thin as 1nm , Since this value was the same to the transition layr thickness of atomically abrupt Si-SiO2 system , we have concluded that the Si/Ge hetero interface was atomically abrupt.Mono-layr adsorption of Ge on Si(100) surface was achieved by 15 cycles exposure of GeCl4 and H.Digital deposition of Ge was achieved on this surface by using Ge-ALE.Combining these four elemental techniques, we have fabricated Si7Ge3 manmade crystals and confirmed the layred structure of Si and Ge.