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

The radiative properties of a-Si0.6N0.4:Hla-Si3N4:H multilayer structures a re studied and compared to those of homogeneous a-Si1-xNx:K films with x in the range 0.35-0.60. Transmission electron microscopy (TEM) shows interfac e abruptness in the multilayers. The photoluminescence (PL) efficiency of t he multilayer structures is up to an order of magnitude larger than that of the him having the composition of the well layers. This result cannot be e xplained by an interface alloying model. The peak emission energy increase with decreasing well layer thickness is simulated in terms of spatial and q uantum confinement models. The latter, associated with a disorder increase, gives the best fit. (C) 2000 Elsevier Science B.V. All rights reserved.