|Budget Amount *help
¥7,000,000 (Direct Cost : ¥7,000,000)
Fiscal Year 1994 : ¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1993 : ¥4,500,000 (Direct Cost : ¥4,500,000)
We constructed a sample holder which can cool to low temperature and measure physical proparties during growth of surface atomic layrs. The sample holder was combined with an exsisting RHEED apparatus. Using the instrument, we measured RHEED intensity oscillations, depth distributions of surface elements and surface conductance.
The important factors to govern epitaxy are substrate temperature, deposition rate and atom supplying methods etc. Thus, we changed systematically surface temperatures and deposition rates, during Ag and Cu deposition on Si (111) surface. As a result, we obtained following results. (1) When surface temeperature was decreased to 160 K,many RHEED intensity oscillations (20-46 peaks) were observed compered with at room temperature, (2) For higher deposition rate of 20ML/min. many RHEED oscillation peaks were observed.(3) These experimental results show that the change of surface temperatures and deposition rates induce the change of diffusion length. Considering th
e effects, we proposed a new growth modes.
When Au was deposited on a Si (111) -ROO<3>*ROO<3>-Ag surface, we found new growth modes "substitution atom growth mode" and "floating atom growth modes". To study the stability of the structures, we heated these surface to higher temperatures. As a result, these surface structures were stable under about 300ﾟC.However, they were unstable and change to an alloy above 400ﾟC.These results are not contradict to the old phase diagram of Au-Ag alloy. Thus, our results implying that the stability of the Au-Ag alloy must be reexamine considering the surface effects. This is a new essential problem on the stability for Au-Ag alloy.
During Ag deposition on the Si (111) -ROO<3>*ROO<3>-Ag surface, we found new surface structures, ROO<21>*ROO<21>-Ag and 6*6-Ag. These structures showed diffrent surface conductance and their behaviors during epitaxy. This means that the surface conductance measurements gives very important infomations for surface structure study. Less