Abstract: A method is described for the atmospheric pressure sintering of silicon to form high density polycrystalline silicon preforms that optionally may be annealed at higher temperatures to form wafers suitable for use in solar cells. The preforms are formed from nanometer scale, high surface area silicon that is sintered to form the near “full density” polycrystalline silicon preforms. Subsequent annealing of the preforms may be used to grow grains suitable for use as wafers for solar cells. The polycrystalline silicon may be used directly to form semiconductor structures other than wafers suitable for solar cells, such as to form electrodes, electrode surfaces, and thermoelectric devices.

Abstract: A sintered aluminum nitride substrate having a thermal conductivity of about 60 W/m-K to about 150 W/m-K, a flexural strength of about 200 MPa to about 325 MPa, a volume resistivity of greater than 1010 Ohm cm, a density of at least about 95% of theoretical, optionally at least 97%, and a reflectance factor of at least about 60% substantially over the wavelength range of 360 nm to 820 nm. A low temperature process for sintering aluminum nitride includes providing an AlN sintering formulation of AlN powder and a sintering aid of yttria, calcia, and optionally added alumina, forming the AlN sintering formulation into a green body, and sintering the green body at a temperature of about 1675° C. to 1750° C.