Glow discharge optical spectroscopy has been demonstrated to be capable of obtaining chemical composition vs depth information in microvolume solid samples. Sample geometry and sputtering pressure were found to have a large effect on measured multilayer interface sharpness. The use of a sample backing plate which has a similar electrical conductivity and a larger cross−sectional area than the sample to be analyzed was found to greatly increase the interface depth resolution. Results are presented for GDOS−determined boron implantation and phosphorus diffusion profiles in Si. The measured profiles appear somewhat broader than expected from theory and possible explanations for this discrepancy are discussed.