New Technique to Advance Semiconductor Performance By MATTHEW FORDAHL    (AP) -- In an advance that could lead to lighter spacecraft and smarter cars, researchers have developed a new technique for producing a high-quality semiconductor that's much more resistant to extreme conditions than the silicon found in most of today's electronics.    Devices built with the rugged material would not require cooling and other protections that add size, weight and cost to traditional silicon electronics in power systems, jet engines, rockets, wireless transmitters and other equipment exposed to harsh environments...