The red and blue luminescence in silicon nanocrystals with an oxidized, nitrogen-containing shell

Traditionally, two classes of silicon nanocrystals (SiNCs) are recognized with respect to their light-emission properties. These are usually referred to as the red and the blue emitting SiNCs, based on the spectral region in which the larger part of their luminescence is concentrated. The origin of the blue luminescence is still disputed and is very probably different in different systems. One of the important contributions to the discussion about the origin of the blue luminescence was the finding that the exposure of SiNCs to even trace amounts of nitrogen in the presence of oxygen induces the blue emission, even in originally red-emitting SiNCs. Here, we obtained a different result. We show that the treatment of red emitting, already oxidized SiNCs in a water-based environment containing air-related radicals including nitrogen-containing species as well as oxygen, diminishes, rather than induces the blue luminescence.