The role of amorphous silicon nanoparticles (a-Si NPs) in electroluminescent characteristics of oxidized amorphous silicon nitride (a-SiN(x):O) light-emitting devices (LEDs) has been studied. A-Si NPs with a high density of 1 x 10(12) cm(-2) are formed in the a-SiN(x):O films after rapid thermal annealing at 900 degrees C for 40 s. A notably enhanced electroluminescence (EL) is obtained from the a-Si-in-SiN(x):O devices and the EL peak position can be tuned from red to green-yellow by controlling the forward voltage. Compared to EL of the a-SiN(x):O device, the turn-on voltage can be reduced to 3 V and the EL power conversion efficiency can be almost six times higher. The improved performance of the LEDs is ascribed to the effective carrier injection due to introduction of high density a-Si NPs. (C) 2010 Elsevier B.V. All rights reserved.