STRUCTURAL AND ELECTRICAL-PROPERTIES OF POLY-SIGE THIN-FILMS PREPAREDBY REACTIVE THERMAL CVD

Polycrystalline thin films of SixGe (0.95 greater than or equal to x g reater than or equal to 0.05, poly-SiGe) were prepared on SiO2 and gla ss substrates by thermal chemical vapor deposition (CVD) from Si2H6 an d GeF4 at 450 degrees C. The Ge-rich films had a high crystallinity ow ing to the direct nucleation of crystallites on the substrates. The cr ystallinity of Si-rich films, however, depended on the growth rate, an d the direct nucleation was achieved at smaller growth rates, leading to improvement of the crystallinity. All the films were p-type regardl ess of film composition, whose carrier concentration decreased from 10 (18) cm(-3) to 10(12) cm(-3), and the Hall mobility from 100 cm(2)/Vs to 1 cm(2)/Vs with an increase in the Si content in the films. The Hal l mobility was improved up to 8 cm(2)/Vs in the film prepared at a gro wth rate of 3.6 nm/min. (C) 1998 Elsevier Science B.V. All rights rese rved.