THE FORMATION OF GERMANIUM NANOCRYSTALS BY THERMAL ANNEALING OF A-SIOX-H A-GEOX-H MULTILAYERS/

Multilayer Films consisting of alternating sublayers of hydrogenated a morphous silicon oxide and germanium oxide were prepared. by dual magn etron sputtering of silicon and germanium targets in an argon/water va por atmosphere. The number and thickness of the a-GeOx:H sublayers ran ged from one to eight and from 80 to 7 nm, respectively. The structure of the multilayers and their components were investigated by means of optical transmission and reflection, infrared spectroscopy, wide-angl e X-ray scattering, and X-ray reflectometry. Upon annealing, first an ordering of the amorphous germanium oxide network connected with an ou tdiffusion of oxygen and an increase of the surface roughness are obse rved. Depending on sublayer thickness, the onset of the formation of G e nanocrystals is observed around 700 K. Crystallization of the german ium oxide sublayers is nearly completed at 870 K. and the crystallite diameter ranges from 4 to 13 nm depending on sublayer thickness. With crystallization the surface roughness decreased and the structure of t ile silicon oxide was improved.