Optical evaluation of doping concentration in SiO2 doping source layer for silicon quantum dot materials

We have investigated and proposed a simple method to correlate optical absorption with high B doping concentrations in thin SiO2 films that offer a potential doping source for Si quantum dots. SiO2 films with boron and phosphorus were deposited using a computer controlled co-sputtering system. By assessing the absorption coefficients, it was observed that the doping can dramatically increase the absorption of the transparent SiO2. Additionally, the highly doped SiO2 films have a very broad Urbach like absorption tail and the absorption corresponds well with the doping level.