The influence of surface pretreatments by remote hydrogen and/or argon plasma on the silicon nucleation density on thermally grown SiO2 in the early stages of low pressure chemical vapor deposition (LPCVD) using monosilane (SiH4) has been studied to control the areal density of Si quantum dots (Si-QDs) on SiO2. In the remote H-2 (or D-2) plasma treatments prior to SiH4-LPCVD, the formation of Si-OH (Si-OD) surface bonds, which act as reactive sites, was confirmed from no changes in the SiO2 surface microroughness and in the thickness. In fact, by a H2 plasma pretreatment, the areal density of Si-QDs as high as 7 x 10(10) cm(-2) was obtained in the LPCVD condition of the dot density with as low as 6 x 10(8) cm(-2) on as-grown SiO2. By changing the pressure and the substrate temperature in the H-2 plasma pretreatment, the dot density was controlled in the range of 4 x 10(9) to 7 x 10(10) cm(-2). Further increase in the dot density and improvement of the dot size uniformity was also demonstrated by the pretreatment of Ar plasma followed by H-2 plasma, presumably because of improved uniformity and integrity in SiO2 surface coverage with OH bonds just before LPCVD. (c) 2004 Elsevier B.V. All rights reserved.