Rectifying characteristics of sputter-deposited SiGe diodes

Schottky and pn junction diodes with good rectifying characteristics have been prepared based on the polycrystalline SiGe (poly-SiGe) thin film deposited by the ion-beam-sputtering (IBS) technique. Boron and phosphorus diffusion techniques have been used to dope and crystallize as-deposited amorphous SiGe film. Rectification ratios as high as 4000 and 1800 have been achieved in Pt/n-poly-SiGe and Ti/p-poly-SiGe Schottky diodes, respectively, while rectification ratio higher than 1500 and breakdown voltage higher than 200 V have been achieved in poly-SiGe pn junction diodes. Schottky barrier height has been determined to be 0.62 and 0.59 eV for Pt/n-poly-Si0.81Ge0.19 and Ti/p-poly-Si0.81Ge0.19 contacts, respectively, which indicates that the band alignment of poly-SiGe may be substantially different from that of epitaxial SiGe.