(Invited) Insights into the UV-C Optical Absorption of AlN Substrates Grown by PVT

The structural and optical properties of 2-inch AlN substrates grown by physical vapor transport were assessed. Ultraviolet transmittance and absolute reflectance spectra were measured spectrophotometrically. Accurate absorption coefficients were calculated with a method accounting for reflection losses. Production of high-quality, macrodefect-free AlN substrates possessing absorption coefficients at 265 nm with values from 30 to 50 cm -1 was demonstrated.