Electrical behavior of MIS devices based on Si nanoclusters embedded in SiOxNy and SiO2 films

We examined and compared the electrical properties of silicon rich oxide (SiOx) and silicon rich oxynitride (SiOxNy) layers integrated in metal-oxide-semiconductor device. The aim of such a study consists in fabricating thin layer for future electroluminescent devices doped with rare earth ions (RE) which benefit from the efficient sensitizing effect of Si nanoclusters (Si nc) towards the RE ions. Thus, one of the key parameters is to overcome the insulating characteristic of the SiO2 matrix by incorporating nitrogen. The technique used for the deposition of such layers is the reactive magnetron sputtering of a pure SiO2 target under a mixture of hydrogen/argon plasma in which nitrogen is incorporated in the case of SiOxNy layer. Two thicknesses of 30 and 65 nm were deposited for each layer, which was subsequently submitted to an optimized annealing treatment. Al/Si nc-SiOxNy/p-Si and Al/Si nc-SiOx/p-Si devices were fabricated and electrically characterized. First results showed a high rectification ratio (>104) for the SiOxNy based device and a resistive behaviour when nitrogen was not incorporating (SiOx based device). For rectifier devices, the ideality factor depended on the SiOxNy layer thickness. The conduction mechanisms of both MIS diode structures were studied by analysing thermal and bias dependences of the carriers transport in relation with the nitrogen content, the Si nc density, and the layer thickness. Finally, a Nd-doped SiOxNy layer was fabricated and tested.