How large is the percentage of non silicon materials in overall production capacity for semiconductors?
How large is the percentage of these non silicon materials in overall
  production capacity for semiconductors?


The best thing is to look at market share, because the only people that are interested in this info are interested in global market trends. Entites aggregating this info are not interested in chip area, so you probably won't find that, and that doesn't really matter because a Sic mosfet will have a different area than a different device such as an LED. There are a few reports like these: 


Source: https://www.technavio.com/report/global-compound-semiconductor-market?utm_source=t4&amp;utm_medium=bw&amp;utm_campaign=businesswire


Source: https://www.openpr.com/news/1162014/Compound-Semiconductor-Market-Trends-and-Growth-Segmentation-and-Key-Companies-IQE-PLC-Sumitomo-Electric-Industries-SCIOCS.html