Study of optimization of Al/a-SiC:H Schottky diodes by means of annealing process of a-SiC:H thin films sputtered at three different hydrogen flow rates

The aim of the present work is to study the optimization of the electrical and optical properties of a-SiC:H Schottky diodes using thermal annealing process to a-SiC:H thin films in the range from 300C up to 675C. The films were deposited onto c-Si(n) using the rf sputtered method at three different hydrogen flow rates, 9sccm, 14sccm, and 20sccm. Subsequently, Al dots evaporated onto a-SiC:H in order to form Schottky contacts. The measurements of logI-V characteristics have shown that the Al/a-SiC:H Schottky diodes are optimized at 550C, 575C, and 600C , for hydrogen flow rates 9 sccm, 14 sccm and 20 sccm respectively. At these temperatures the logI-V curves are linear for more than seven orders of magnitude, and the majority carries are transported by thermal emission mechanism. The measurements of optical response of these diodes present two maximum values (>70%), one in the range from 550nm up to 625nm and the other at 850nm which are attributed to Al/a-SiC:H junction and to a-SiC:H/c-Si(n) heterojunction, respectively. From the overall study of the electrical and optical measurements of the Schottky diodes it is concluded that at hydrogen flow rate 20 sccm and annealing temperature 600C is achieved the optimum Al/a-SiC:H Schottky diode. This result is in full agreement with the properties of the a-SiC:H.