ELECTRICAL AND STRUCTURAL CHARACTERIZATION OF PTSI P-SI1-XGEX LOW SCHOTTKY-BARRIER JUNCTIONS PREPARED BY COSPUTTERING/

Schottky barrier junctions of PtSi/Si1-xGex were produced; the silicid e was deposited by co-sputtering on defect-free well-calibrated strain ed-Si1-xGex (0 less than or equal to x less than or equal to 0.242) la yers. This work is motivated by the fact that it is very difficult to control the formation of well-defined and well-controlled PtSi/Si1-xGe x junctions by reacting Pt/Si1-xGex or by using a silicon cap layer. T he Schottky barrier heights of these junctions were substantially lowe r than those of PtSi/Si junctions. Different characterization tools we re employed for structural characterization. High-resolution multicrys tal x-ray diffraction (HR-MCXRD) was used to investigate the sample qu ality and strain state of the molecular beam epitaxy (MBE) grown Si1-x Gex layers and to accurately determine the Ge fraction in the fabricat ed junctions. Cross-sectional transmission electron microscopy (XTEM) was applied to investigate the interface roughness. The possible inter layer diffusion was investigated by secondary ion mass spectrometry (S IMS). The variation of the barrier height of the junctions with the Ge fraction x was studied, and it was found to follow the same change as the band gap of strained-Si1-xGex. Also, and for comparison, Pt/p-Si1 -xGex junctions were produced, and the effect of annealing on electric al characteristics was investigated. (C) 1997 American Vacuum Society.