THIN-FILM GROWTH OF SEMICONDUCTING MG2SI BY CODEPOSITION

Ultrahigh vacuum evaporation of magnesium onto a hot silicon substrate (greater than or equal to 200 degrees C), with the intention of formi ng a Mg2Si thin film by reaction, does not result in any accumulation of magnesium or its silicide. On the other hand, codeposition of magne sium with silicon at 200 degrees C, using a magnesium-rich flux ratio, gives a stoichiometric Mg2Si film which can be grown several hundreds of nm thick. The number of magnesium atoms which condense is equal to twice the number of silicon atoms which were deposited; all the silic on condenses while the excess magnesium in the flux desorbs. The Mg2Si layers thus obtained are polycrystalline with a (111) texture. From t he surface roughness analysis, a self-affine growth mode with a roughn ess exponent equal to 1 is deduced. (C) 1997 American Institute of Phy sics.