Photoluminescence Imaging of Semiconductors

Abstract

The development of energy-related devices requires new materials and fabrication processes that enable both an enhancement in performance and a decrease in manufacturing cost. Polycrystalline semiconductors are promising for photovoltaic applications because they can be grown at low temperatures on inexpensive substrates. Metamorphic epitaxy of semiconductor alloys on latticemismatched substrates is also increasingly used to access new semiconductor alloys for visible light emitting diodes used in high efficiency solid-state lighting. With these advancements, defects play a progressively more prominent role in device performance, and it is important to be able to probe their behavior in order to understand and ultimately control their effects. Information about the spatial distribution of extended defects and compositional fluctuations as well as their influence on carrier transport is particularly crucial for materials engineering efforts. Characterization techniques must therefore be able to provide real time feedback with micron-scale spatial resolution. We present a novel photoluminescence (PL) imaging technique with both of these capabilities and discuss the information that can be obtained in a number of semiconductor systems.