I-Corps: A New Approach to Silicon/Compound Semiconductor Integration

Columbia University, New York NY

Investigators

Abstract

A monolithically integrated LED array is being developed with applications in the projection display industry and other non-display market areas such as scanning, computational photography, and depth analysis. The team's process begins with a compound semiconductor LED wafer upon which individual LED pixels are lithographically patterned to create a display. Light is generated from each individual LED pixel only where and when needed for the display. Both an active and passive matrix version are under development, the active matrix version uses laser crystallized polycrystalline silicon, whereas the passive matrix version takes advantage of direct addressing and/or rectification in the LEDs. The final calculated light path efficiency is approximately 75%, which represents a 5-10X improvement over the efficiency in current commercial systems. The reduced parts count allows for a smaller total system size, a smaller bill of materials, and a dramatically-decreased system cost for both direct view and projection microdisplays. This approach increases the brightness, decreases the cost, and reduces the overall size of this class of displays, eliminating the obstacles for mainstream adoption of this system in display and non-display markets. This system has the potential to develop a picoprojector with a power efficiency, brightness, cost, and form factor unavailable in incumbent systems. In addition to applications in displays, picoprojectors with this efficiency, brightness, and form factor can be used in a number of other applications including depth imaging, in-situ guidance for medical procedures, and computational photography. Commercialization of this device will impact all of these areas and enable a range of new downstream applications. This approach will also demonstrate the potential for commercial integration of compound semiconductors with silicon using laser recrystallization. This approach also has the potential to impact a range of other devices that currently use silicon backplanes integrated with compound semiconductor devices, such as focal plane imagers. These devices, which are primarily used in hyperspectral imagers today, have a range of applications in the medical, military, earth science, and metrology space and further development in this area has the potential to impact these project areas as well.