INFRARED-SPECTROSCOPY AND SECONDARY-ION MASS-SPECTROMETRY OF LUMINESCENT, NONLUMINESCENT, AND METAL QUENCHED POROUS SILICON

Porous silicon with varying optical properties (luminescent, nonlumine scent, and metal quenched) is investigated by transmission infrared (I R) spectroscopy and secondary ion mass spectrometry (SIMS). SIMS and t ransmission IR data are presented which show a lack of correlation bet ween the optical properties of similarly prepared luminescent and nonl uminescent porous silicon samples and the concentrations of the chemic al elements and bonds detected therein. Similar results are obtained f or a comparison of IR spectra before and after dissolving the topmost layers (approximately 2000 angstrom) of a luminescent sample in a KOH solution, exposing the nonluminescent porous material below. Finally, IR and SIMS results for luminescent porous silicon quenched by metal i on solutions show a large increase in oxygen after quenching, but it i s argued that the increased oxygen is unlikely to be directly responsi ble for the quenching of luminescence.