a-SiN:H multilayer versus bulk structure: a real improvement of radiative efficiency?

The radiative properties of a-Si0.6N0.4:H/a-Si3N4:H multilayer structures are studied and compared to those of homogeneous a-Si1 − xNx:H films with x in the range 0.35–0.60. Transmission electron microscopy (TEM) shows interface abruptness in the multilayers. The photoluminescence (PL) efficiency of the multilayer structures is up to an order of magnitude larger than that of the film having the composition of the well layers. This result cannot be explained by an interface alloying model. The peak emission energy increase with decreasing well layer thickness is simulated in terms of spatial and quantum confinement models. The latter, associated with a disorder increase, gives the best fit.