Inquiry about AlN Material for 12-inch heater plate

Dear Sir/Madam,
We are looking for an AlN material that meets the following specifications:
-Sintered body purity: ≥99.5% (based on metallic impurities)
-Density: ≥3.2 g/cm3
-Flexural strength: ≥310 MPa
-Thermal conductivity: ≥160 W/(m.K)
-Electrical resistivity: ≥1012 Ω∙cm
-Surface roughness after rapping (RA): 0.8=1.0 nm
The intended application is for a semiconductor heater plate.
We have a question and two requests:
1. Could you provide a material that meets the above specifications for a heater size for 12-inch wafers?
2. We would like to request a quotation for a sintered body with the following dimensions after grinding:
Diameter 350 mm x Thickness 6 mm.
3. Since we cannot proceed with the use of your material without verification of the above properties, we kindly request provision of a sample.
Since the measurement and evaluation of these properties require significant cost, we kindly ask you that you provide the sample only if your material meets the specified requirements.
We appreciate your support and look forward to your reply.
Best regards,
Young-Wook
Head of Materials Development Division