Fabrication of nanosilicon ink and two-dimensional array of nanocrystalline silicon quantum dots

An assembly of nanoparticles using a colloidal solution is promising for the fabrication of future highly integrated electron and photoelectronic devices because of low manufacturing cost, flexible substrates, and alternative methods that can overcome the limitation of top-down technology. We have successfully prepared two-dimensional arrays of nanocrystalline silicon (nc-Si) quantum dots with a uniform size of 10 nm. However, the area of two-dimensional arrays has been limited because of the problems of dissolution in water and agglomeration of nc-Si due to a high surface reactivity. The key issue is the surface modification of nc-Si particles. In this study, we have demonstrated the evaluation of surface modification states of nc-Si QDs by zeta potential and particle size distribution measurements. As a result of the optimization of the surface modification process, we have successfully obtained a well-dispersed nc-Si QD solution, namely, nanosilicon ink. Furthermore, we have successfully fabricated a two-dimensional array of nc-Si QDs using the Langmuir-Blodgett film method in the entire 1 × 1 cm2 silicon substrate.