Effects of low-thermal-budget treatments on the porous Si material properties

Our interest in porous silicon is due to its potential benefits in crystall ine Si solar cells. Besides the use as an anti-reflection coating, the poro us layer also acts as a light-diffusor. However major drawbacks are the sig nificant light absorption within the porous layer and both insufficient as well as unstable surface passivating capabilities. The unstable nature of t he porous Si is also reflected in the presence of suboxides after storage i n ambient. In this work we focus on rapid-thermal-oxidation (RTO) and plasm a-nitridation as low-thermal-budget chemical modification techniques in ord er to obtain a surface layer with a controlled and stable structure and com position. RTO of porous Si converts the material into SiO2 in conjunction w ith a drastically decreased porosity. Both a remote- and a direct-plasma ni tridation of porous Si are able to incorporate nitrogen uniformly throughou t the porous layer while preserving the porous character.