Whatever happened to SOI-Tronics after it changed its name to Silicon Evolution? 

The answer is that the company was purchased, and then failed its second round of funding, forcing it into bankruptcy. As it was put in a press release issued by the company that then owned their pioneering technology:

January 29, 2002 ... "Isonics further announced that it has hired Dr. Hans Walitzki as Vice President of Advanced Wafer Technology. Dr. Walitzki, who received a PhD in Physics from Bonn University in Germany, worked for 15 years in senior management positions in manufacturing, technology and product management at Wacker Siltronic, a leading silicon wafer manufacturer. In 1997 Dr. Walitzki co-founded Silicon Evolution, Inc. (SEI), which successfully manufactured silicon-on-insulator wafers and sold them to a wide range of customers. In September 2001, Isonics acquired exclusive rights to SEI's intellectual property for manufacturing low cost SOI and other types of silicon wafers. After an anticipated second funding round failed to materialize, SEI filed Chapter 7 bankruptcy in late 2001 and is in the process of being liquidated "We are very fortunate to have Dr. Walitzki on our team," James E. Alexander Isonics' Chairman & CEO commented. "His first task is to implement certain of the SEI technology into the manufacturing process at Silicon Quest, our SOI alliance partner. The fact that we have shipped our first SOI product wafers in such a short time is evidence that this relationship and the technology are working well." ...

The full news release is available at: http://www.siliconquest.com/chn/products/news_release.htm