Charging states of Si quantum dots as detected by AFM/Kelvin probe technique

Hemispherical Si quantum dots have been self-assembled on thermally grown 3 .2-nm-thick SiO2/p-Si(100) by low-pressure chemical vapor deposition of sil ane. The charging states of the Si quantum dots have been detected as surfa ce potential changes by using an atomic force microscopy/Kelvin force probe method. From the relationship between the measured surface potential chang es and the charging energy of a single dot, the number of electrons retaine d in a dot has been estimated to be one. Furthermore, it is found that elec tron extraction from neutral dots can be achieved to create a hole at each dot.