Study of Ga⁺ implantation in Si diodes: effect on optoelectronic properties using micro-spectroscopy

Ion implantation has been widely used in various device fabrication applications, including that of optoelectronic components. Focused Ion Beam (FIB) is an especially versatile implantation method, since it can be used for well controlled doping with sub-micron spatial precision. Here, we report FIB induced gallium doping in micrometer-sized regions on shallow Silicon p-n junction devices and its effect on the device optoelectronic properties investigated through micro-spectroscopic measurements. The effect of varying dose levels has been quantified in terms of photo voltage, Raman spectroscopy, XPS and reflectance measurements to investigate the effect of radiation damage and surface amorphization. Based on these observations we report simultaneous occurrence of two scenarios, channeling of high-energy gallium ions beyond the junction depth, as well as formation of an amorphous silicon layer, which cumulatively degrade the optoelectronic properties of the diodes.