Transparent silicon solar cells can lead to an increased efficiency of silicon‐based multi‐junction assemblies by transmitting near and below band gap energy light for conversion in a low band gap solar cell. This analysis shows that the maximum efficiency gain for a low band gap solar cell beneath silicon at a concentration of 50 suns is 5.8%, based on ideal absorption and conversion of the photons. This work analyzes the trade‐offs between increased near band edge absorption in the silicon and silicon solar cell transparency. Application of these results to real cases including a germanium bottom solar cell is analyzed, leading to a range of cases with increased system efficiency. Non‐ideal surfaces and real silicon and germanium solar cell device performance are presented. The range of practical system gains may be as low as 2.2 – 1% absolute when compared with the efficiency of a light‐trapped silicon solar cell for 1‐sun operation, based on this work. Copyright © 2012 John Wiley & Sons, Ltd.

In this presentation we will discuss the performance and limitations of our 220 channel video rate passive millimeter wave imaging system based on a distributed aperture with optical upconversion architecture. We will cover our efforts to reduce the cost, size, weight, and power (CSWaP) requirements of our next generation imager. To this end, we have developed custom integrated circuit silicon-germanium (SiGe) low noise amplifiers that have been designed to efficiently couple with our high performance lithium niobate upconversion modules. We have also developed millimeter wave packaging and components in multilayer liquid crystal polymer (LCP) substrates which greatly improve the manufacturability of the upconversion modules. These structures include antennas, substrate integrated waveguides, filters, and substrates for InP and SiGe mmW amplifiers.

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Thin crystalline silicon layers on an insulating ceramic substrate permit the realization of a seriallyinterconnected monolithic array. In this paper we present the device design and fabrication issues relating to such a monolithically integrated device, and the latest results are presented. A novel device process is presented that involves isolating and re-interconnecting silicon solar cell elemcnts on an insulating ceramic substrate. Device efficiencies of 7.3% have been achieved. and are presently limited by high series resistance and chemical impurities.