A new visible photoluminescence in the conducting Ta-Si-N nanocomposite thin films

The conventional visible photoluminescence (PL) behavior at room temperature (RT) is observed in the semiconducting or insulating nanostructured materials with large bandgaps. Here, we have demonstrated the visible-color PL behavior at RT of the conducting Ta-Si-N thin films nanocomposite using simple magnetron sputtering without any post annealing. X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) depth profile results evidence that the microstructure of conducting Ta-Si-N with a low resistivity of 220-375 μΩ cm exhibits (Tax,Siy)N nanocrystalline grains embedded in an amorphous matrix, which can emit the distinct PL intensity from 390 to 750 nm wavelengths. No PL is detected in the coarse-grain polycrystalline films. Qin's extended quantum confinement/luminescence center model [G.G. Qin, Mater. Res. Bull. 33 (1998) 1857-1866] was adopted and modified to discuss the RT PL mechanism in the conducting Ta-Si-N films using three types of competitive photoexcitation/photoemission processes.