S. Oda, M. Kimura and M. Otobe

Research Center for Quantum Effect Electronics
Tokyo Institute of Technology
O-Okayama, Meguro-ku, Tokyo 152, Japan

Silicon quantum dot structures with size less than 10nm have been fabricated in a glow-discharge plasma of silane and deposited on various substrates at room temperature. Lattice images in TEM observation have revealed that Si quantum dots are spherical in shape and form single domain crystal. The surface of Si quantum dots is covered by natural oxide 1.5nm thick. In an attempt to control diameter of Si quantum dots, we propose a method to separate nucleation and crystal growth. A short pulse of hydrogen gas was inserted in silane plasma to enhance nucleation. A monodispersed Si quantum dot structure with diameter of 8±1nm has been obtained. The effective size of the crystal region is 5nm. Si quantum dots have showed red photoluminescence at room temperature upon excitation by uv light from a He-Cd laser. When Si quantum dots are oxidized at 800oC, the peak of PL spectra shifts toward blue with increasing oxidation time. We have measured current-voltage characteristics from a quasi one dimensional array of Si quantum dots, deposited on ultrasmall (23nm apart) electrode patterns of heavily-doped polycrystalline Si fabricated using EB lithography and ECR etching. Structures due to Coulomb staircase have been observed in I-V curve at room temperature. Silicon Nanoelectronics Workshop, Honolulu (1996)