Low Temperature Semiconductors and High Temperature Superconductors.

Silicon MOS devices show significantly improved performance when operated at 77K while high-T sub c superconductors may allow very high performance and high density transmission lines. It is therefore natural to consider their combination as the basis for high performance systems in which both the local active device performance and the global communications environments are optimized by operation at liquid nitrogen (LN) temperatures. Whereas the performance of silicon CMOS VLSI circuits is increased 2-3 times by simply dunking in LN, the application of high- T sub c superconductors as routine system level interconnections will require extensive development and important breakthroughs. Following a discussion of the marriage of cooled semiconductor devices and "warm" superconducting transmission lines, several practical issues confronting superconducting transmission lines are briefly described.