MODIFICATION OF THE NEAR SURFACE PROPERTIES OF LA YERED SEMICONDUCTING COMPOUNDS BY ION IMPLANTATION O. Amir and E. Lifshitz Department of Chemistry and Solid State Institute Technion, Haifa 32000, Israel INTRODUCTION Many semiconducting materials crystallize in a layered structure. They exhibit anisotropic physical properties and interesting reversible intercalation chemistryl. These properties can be applicable in the utilization of the layered compounds in new and emerging technologies such as: alkali metal batteries, solar devices and electro optical devices z . Many of these applications require enhanced electrical conductivity, n or p- type doping and high crystalline order. Therefore the present paper describes our attempt to alter the near surface electrical and optical properties of Ti n dichalcogenide (SnS2) and Cadmium chalcogenophosphate (CdPS3) by ion implantation technique. These two compounds are broad band semiconductors with Cdlz and CdCI 2 crystal structure respectively. The implantation technique has an advantage over intercalation or diffusion processes in the possibility to insert a variety of ions into a sample controlling their amount and location. However, the process has disadvantage in creating crystal disorder upon implantation. This disadvantage can be overcome by applying annealing process to recover the crystal damage, and retain the highest crystalline order. Usage of ion implantation to change the properties of graphite was studied extensively3 but as for layered semiconductors the only use made of ion implantation, to the best of our knowledge, is for synthesis of the materials MS 2, MS2C and MS2A (M-transition metal A- alkali atoms)4,5. The present work composes of two parts. The first describes implantation of an inactive ion, Ar+, for the study of the damage and annealing mechanisms. The second part presents the utilization of P+ implantation for the alteration of the electrical properties of SnS2 at various annealing temperatures. Rutherford back scattering (RBS) and channeling technique were used in order to characterize the implantation damage, and resistivity and Hall effect measurements were utilized to examine the electrical changes of the samples. The Chemical Physics of Intercalation ll, Edited by P. Bernier et al., Plenum Press, New York, 1993 333