High density energy storage in semiconductor devices is provided. There are two main aspects of the present approach. The first aspect is to provide high density energy storage in semiconductor devices based on formation of a plasma in the semiconductor. The second aspect is to provide high density energy storage based on charge separation in a p-n junction.
 This invention was made with Government support under contract number W911NF-07-2-0027 awarded by the US Army Research Laboratory, and under contract DE-AR0000069 awarded by ARPA-E under the Department of Energy. The Government has certain rights in this invention.