| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming quantum dots by which quantum dots excellent in uniformity can be inexpensively formed on the surface even if it is a high index face of a semiconductor, and a semiconductor element in which nearly circular quantum dots in a plane view are formed by the forming method. SOLUTION: A substrate is irradiated with In for periods of time of t<SB>0</SB>-t<SB>1</SB>, t<SB>2</SB>-t<SB>3</SB>, ..., t<SB>2k</SB>-t<SB>2k+1</SB>. The irradiation of the In to the substrate is stopped for periods of time of t<SB>1</SB>-t<SB>2</SB>, t<SB>3</SB>-t<SB>4</SB>, ..., t<SB>2k-1</SB>-t<SB>2k</SB>. In this way, the irradiation of an In molecule to the substrate and non-irradiation are repeated. While, the substrate is continuously irradiated with As for a period of time of t<SB>0</SB>-t<SB>2k+1</SB>. For example, the substrate is irradiated with the In molecule for 2.5 seconds. After that, a processing sequence for stopping the irradiation to the substrate for one second is repeated ten times. While, the substrate is continuously irradiated with an As molecule for 34 seconds. By this, a two-dimensional epitaxial film is formed until its film thickness becomes a critical film thickness. After the film thickness becomes the critical film thickness, the irradiation contributes to the growth of a grain being a core of the quantum dot. COPYRIGHT: (C)2006,JPO&NCIPI |
