| abstract |
The handle substrate 2A of the composite substrate for semiconductors is composed of polycrystalline light-transmitting alumina, the purity of which is 99.9% or more, and the polycrystalline light-transmitting alumina is in front of the wavelength range of 200 to 400 nm. The average value of the total light transmittance is 60% or more, and the average value of the linear transmittance in the wavelength range of 200-400nm of the polycrystalline light-transmitting alumina is 15% or less. |