Porous silicon surface stability: a comparative study of thermal oxidation techniques

In this report, a systematic study is carried out to check the superiority of the oxidation techniques employed for improving the surface stability of Porous Silicon (PS). PS samples were oxidized in three different atmospheres viz. ambient air, oxygen gas and the mixture of oxygen and nitrogen gas. Among them, samples oxidized under O2 atmosphere proves to be the best yielding excellent stable surface and no degradation observed even after one year. The qualitative analysis of the surface morphology, surface bond termination, and degradation, if any, of the oxidized PS samples were done by scanning electron microscope, micro-Raman, Photoluminescence and Fourier Transform Infrared spectroscopy. Electrical capacitive technique is used to check the ageing effect of the sensor device made from thermally oxidized PS. Ethanol vapor sensing was periodically made in the range of 25–100 ppm for one year, and any noticeable degradation is not observed in its sensing performance.