Quantum size effects on the optical band gap of microcrystalline Si:H

We have succeeded in fabricating the mostly crystallized Si:H materials having a wide optical band gap of up to 2.4 eV by means of a reactive sputtering technique with a low substrate temperature of ∼100 K. The structural analysis showed that the materials consist of small crystalline silicon particles surrounded by hydrogen atoms, whose diameters are 20–30 Å. The widening of the optical band gap can be explained by a three-dimensional quantum-well effect in the small particles.