Visible electroluminescence from crystallized a-Si:H/a-SiNX:H multiquantum well structures

Visible photoluminescence (PL) in crystallized a-Si:H/a-SiNX:H multiquantum well (MQW) structures is reported for the first time. In this paper new results are presented on visible electroluminescence (EL) from these novel luminescent structures. The MQW heterostructures consisting of 40 layers were formed by PECVD method and then crystallized by Ar ion laser annealing technique. The crystallized samples with well layer thickness, L(S) = 4 nm, showed an intense visible PL peaked similar to 2.0 eV. The experimental EL cells are of the form of semitransparent metal/crystallized a-Si:H/a-SiNX:H MQWs/p(+)-a-Si:H/quartz substrate. When the forward current density reaches a certain value, stable visible (orange) light is observed by the naked eye. A possible explanation of this light emission is the radiative recombination due to the carriers injection into quantized states in nano-size Si crystallites within the Si potential wells.