|Budget Amount *help
¥7,700,000 (Direct Cost : ¥7,700,000)
Fiscal Year 1997 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Fiscal Year 1996 : ¥6,000,000 (Direct Cost : ¥6,000,000)
In 1996, we have investigated the nucleation of SiGe and selective growth of the films in a reactive thermal CVD with GeF4 and Si2H6 for improvement of film crystallinity The major attention was paid to the gas flow ratio, growth temperature, pressure, and film composition. It was found that the direct nucleation took place on SiO_2 substrates irrespective of film composition : in the growth condition for Ge-rich films at 375ﾟC,nucleation density was controlled in a range of 10^<6-12>cm^<-2> and in the condition for Si-rich films at 450ﾟC,the density in a range of 10^<9-12>. cm^<-2>The selective film growth of SiGe films SiO_2/Si substrates was well established on SiO_2 substrate by tuning the growth pressure while the other growth parameters were kept constant.
In 1997, preparation of high crystallinity polycrystalline SiGe have been carried out, based on the previous results on the control of nucleation at the early stage of the film growth and successive selective growth of the resulting nuclei to the grains. This was easily achieved by tuning the growth pressure for the selective growth after forming the nuclei at a higher pressure. The high cyrstllinity poly-SiGe thin films were successfully prepared at 375ﾟC for Ge-rich films and 450ﾟC for Si-rich films, in which the crystallinity was very much improved and no inhomogeneity of crystallinity was observed.
The significant improvement of the film quality was clearly confirmed by XRD,TEM,and Hall measurement studies.