Transmission electron microscopy study of PtSi/Si (p-type) composites grown on Si(111) substrates

A transmission electron microscopy (TEM) study was made of PtSi/Si (p-type) composite films grown on Si(lll) substrates. The films, 3-mu m thick, were prepared by sputtering from a Pt-Si target consisting of 81 at.% Si and 19 at.% Pt. They were subsequently annealed ill argon at 575 degrees C for 7. 5 h. TEM indicated a dense aggregation of PtSi particles 50 nm and smaller in size, concentrated in a surface region about 500 nm thick. Resistivity m easurements on this segregated layer showed that it was p-type with a resis tivity of 3 x 10(-3) Omega cm. Below this the structure is constant right d own to the Si(111) substrate and consists of PtSi particles 10 nm in size c lustered around the Si matrix. The Si is partly crystalline (10 nm particle s) and partly amorphous. The resistivity of this layer is on the order. of 100 Omega cm. These results are attributed to the movement of the PtSi part icles in the bulk composite film toward the surface where they exist in a l ower energy configuration. A microprobe analysis of these films showed 78 a t.% Si and 12 at.% Pt. (C) 2000 Elsevier Science S.A. All rights reserved.