Self-Assembling of Silicon Quantum Dot and Its Electronic Characterization

Formation of Si quantum dot array on ultrathin SiO2 is a key to develop a silicon-based resonant tunneling device[1] or quantum-dot floating-gate MOS memory[2]. In order to achieve room temperature operation of such quantum dot devices, the dot size should be as small as 3nm as evaluated by a simple quantum box model or coulombic charging energy. Recently it is demonstrated that Si quantum dots can be spontaneously produced on SiO2 by controlling the early stages of low-pressure chemical vapor deposition(LPCVD) of SiH4[1, 3]. For the purpose of the device application the dot size distribution should be minimized and the dot density per unit area must be as high as 1012/cm2. This paper describes a formation mechanism of nanometer-scale Si dots on SiO2 during LPCVD and a possible route to control the size distribution and the areal density of Si dots.