Optimization of the Contact Resistance in the Interface Structure Al/a-SiC:H N-Type by Thermal Annealing for Optoelectronics Applications

The presented process meets the requirements for integration of amorphous silicon carbon films for the development of large optoelectronics devices such as LED´s and IC technology into complete optoelectronic systems. The key enabler for this integration scheme is the low temperature of deposition of films and an ohmic behavior in the interface metal/silicon carbide. In this work the optimization of the interface contact resistance of Al/a-SiC:H films is studied by means of thermal annealing timing. The films were deposited by enhanced chemical vapor deposition (PECVD). The a-SiC:H films were prepared from CH₄/SiH₄ and C2H2/SiH4 mixtures. Structural and optical properties of the deposited films are also presented. An implantation phosphorous dose was used for doping before fabrication of patterned aluminum contacts. The implanted films were electrical characterized by transfer length method (TLM) measuring a sheet resistance value as low as 160 MΩ/square. The Schottky behavior was improved to ohmic behavior after several hours in thermal treatments annealing at 350ºC, which allows to obtain a reasonable contact resistance values in the range from 8.6KOhm to 23.4K