Study of surface structure by using a quasi one-dimensional convergent beam RHEED

本研究的目的是缩短反射式高能电子衍射摇摆曲线的测量时间，实现摇摆曲线的高速测量。为了缩短摇摆曲线的测量时间，我们用准一维会聚光束法代替了通常需要20秒左右的变掠射角光强测量。2001年<th>，我们将<st>这种新方法应用于高掺硼硅的动态表面结构变化。当退火时，B原子从体向表面偏聚，（111）表面呈现Si（111）[square root]3×[square root]3-B结构。表面结构有一个有趣的特点，即B原子位于吸附原子下方的S_5位上。S_5位的占有率取决于热处理温度：1200 ℃闪蒸后，B原子占据表面S_5位的70%，950 ℃退火后，占据率达到95%左右。在950 ℃退火过程中，我们观察到了RHEED摇摆曲线，并成功地观察到了RHEED摇摆随B原子表面偏聚的连续变化。

A goal of this study is a shortening in measurement time of reflection high-energy electron diffraction (RHEED) rocking curve and achieving high-speed measurement of RHEED rocking curve. To shorten the measurement time of rocking curve, we used a quasi one-dimensional convergent beam method instead of intensity measurements with varying glancing angle (θ), which takes about 20 sec. In 2000^<th>, we have confirmed that an accurate rocking curve can be obtained in 0.3 sec.In 2001^<st>, we have applied the new method to a dynamic surface structure change When a highly Boron-doped Silicon is annealed, the B atoms are segregated from the bulk to the surface and the (111) surface shows the Si(111) 【square root】3×【square root】3-B structure. The surface structure has an interesting feature that the B atom sits on the S_5 site just below an adatom. The occupancy of the S_5 site depends on thermal treatments : After the flashing at 1200 ℃, the B atoms occupied about 70 % of S_5 sites on the surface ; and the occupancy reaches about 95 % after annealing at 950 ℃. Then we observed RHEED rocking curves from the flashed surface during annealing at 950 ℃ and we succeeded to observe the continuous change in the RHEED rocking with the surface segregation of B atom.