EXAMINATION OF (CRYSTALLIZED A-GE-H) A-SINX-H MULTILAYERS WHICH DISPLAY PHOTOLUMINESCENCE/

A study has been conducted of (crystallized a-Ge:H)/a-SiNx:H multilaye rs which display room temperature photoluminescence in the visible ran ge. The a-Ge:H/a-SiNx:H multilayers were prepared by glow discharge ch emical vapor deposition by changing gas flows in a continuous depositi on using a computer. Crystallization of the a-Ge:H layers was achieved by either thermal annealing in vacuum or exposure to a scanning laser light. The multilayer structure was confirmed by glancing angle X-ray diffraction. Crystallization was confirmed by Raman scattering. When crystallization of the a-Ge:H is achieved using the laser-scanning tec hnique, strong visible photoluminescence with a peak centered around 6 25 nm, independent of the a-Ge:H layer thickness, is observed. The cry stallization is accompanied by severe cracking and pitting of the film . A study of several a-Ge:H/a-SiNx:H layered structures reveals that t his laser-induced crystallization only occurs when the a-Ge:H is in a state of high stress. Further study reveals that a-SiNx:H also photolu minesces with a similarly broad peak in the same wavelength range as o bserved from the crystallized multilayers. Using slow thermal annealin g, it was possible to crystallize the a-Ge:H with minimal physical dam age to the film. Photoluminescence measurements of these quantum-well structures yield a low intensity broad peak in the visible range befor e crystallization which does not change after crystallization. One is led to conclude that the photoluminescence observed in the laser-cryst allized a-Ge:H/a-SiNx:H is from the a-SiNx:H and cannot be attributed to effects of quantum confinement.