US Patent 7763530 Doping of particulate semiconductor materials

The invention relates to a method of doping semiconductor material. Essentially, the method comprises mixing a quantity of particulate semiconductor material with an ionic salt or a preparation of ionic salts. Preferably, the particulate semiconductor material comprises nanoparticles with a size in the range 1 nm to 100 μm. Most preferably, the particle size is in the range from 50 nm to 500 nm. Preferred semiconductor materials are intrinsic and metallurgical grade silicon. The invention extends to a printable composition comprising the doped semiconductor material as well as a binder and a solvent. The invention also extends to a semiconductor device formed from layers of the printable composition having p and n type properties.