US Patent 8686428 Semiconductor device and structure

A device with an external surface, the device including: a substrate including first mono-crystal transistors; a second layer including second mono-crystal transistors, the second mono-crystal transistors overlaying the first mono-crystal transistors; and a plurality of thermal conduction paths from a plurality of the second layer locations to the external surface, wherein at least one of the thermal conduction paths includes an electrically nonconductive contact.