Subcategory: Materials Science
Chavez Lawrence - Pennsylvania State University
Tin Monosulfide (SnS) is an attractive metal chalcogenide for optoelectronic and electronic applications due to its earth abundant constituent elements, intrinsic p-type conductivity, suitable band gap energy of 1.65 eV, and high absorption coefficient. While this semiconductor is attractive, one obstacle to increasing the efficiencies of devices fabricated using SnS is parasitic resistance, such as contact resistance between SnS and a contact metal. This study investigated how low-resistance Ohmic contacts can be fabricated using SnS as the semiconductor. Pd-In was hypothesized to lower contact resistance, since Indium may act as dopant to SnS. Consequently, this compound was contacted to SnS thin films, and the devices were annealed at temperatures ranging from 200–500°C to investigate the effects of annealing on the contact resistance of the metal-SnS system. Similar work was done with Tin Disulfide (SnS2) grown by chemical vapor deposition. Unlike SnS, SnS2 is a layered material and an intrinsic n-type semiconductor, pointing to potential applications in flexible electronic, optoelectronics, and nanoelectronics. The metal contacts were deposited using sputtering with Ar+ plasma, and the contact resistance was measured using circular transfer length method (CTLM) test structures. Contact resistance in the Pd3In7-SnS system was measured to be on the order of 106 Ω•mm whereas the contact resistance reported in the literature of the Pd-SnS system was measured to be on the order of 103 Ω•mm. Furthermore, the annealing degraded the contacts such that the contact resistance could not be calculated with an acceptable degree of error. The data presented in this study suggests that Pd3In7 is not a viable metal for making low resistance Ohmic contacts to SnS. Future work includes using a Pd-Au solid solution as the contact metal to SnS to attempt to combine the benefits that Pd and Au contacts to SnS individually provide.
Funder Acknowledgement(s): The author of this study would like to thank the National Science Foundation for funding this study.
Faculty Advisor: Suzanne Mohney, firstname.lastname@example.org
Role: Metal Deposition. Device Fabrication. Annealing. Resistance measurements.