Developed in collaboration with III-V Lab (Marcoussis, France), a high-density micro-LED array process has been demonstrated by CEA-Leti (Grenoble, France) that targets wearable and nomadic systems through a scalable integrated circuit manufacturing process. CEA-Leti says the high-brightness, enhanced-vision systems such as head-up and head-mounted displays can improve safety and performance in fields such as aeronautics and automotive, where the displays allow pilots and drivers to receive key navigation data and information in their line of sight.
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For consumers, smartglasses or nomadic projection devices with augmented reality provide directions, safety updates, advertisements, and other information across the viewing field. LED microdisplays are ideally suited for such wearable systems because of their low footprint, low power consumption, high-contrast ratio, and ultrahigh brightness.
Leti researchers have developed gallium-nitride (GaN) and indium gallium-nitride (InGaN) LED technology for producing high-brightness, emissive microdisplays for these uses, which are expected to grow dramatically in the next three to five years. For example, the global research firm MarketsandMarkets forecasts the market for head-up displays alone to grow from $1.37 billion in 2012 to $8.36 billion in 2020.
"Currently available microdisplays for both head-mounted and compact head-up applications suffer from fundamental technology limitations that prevent the design of very low-weight, compact and low-energy-use products," said Ludovic Poupinet, head of Leti’s Optics and Photonics Department. "Leti's technology breakthrough is the first demonstration of a high-brightness, high-density micro-LED array that overcomes these limitations and is scalable to a standard microelectronic large-scale process. This technology provides a low-cost, leading-edge solution to companies that want to target the fast-growth markets for wearable vision systems."
Announced during Display Week 2015 in San Jose, CA, the CEA-Leti technology is based on micro-LED arrays that are hybridized on a silicon backplane. Key innovations include epitaxial growth of LED layers on sapphire or other substrates, micro-structuration of LED arrays (10 micron pitches or smaller), and 3D heterogeneous integration of such LED arrays on CMOS active-matrices.
CEA-Leti says these innovations make it possible to produce a brightness of 1 million cd/m² for monochrome devices and 100 kcd/m² for full-color devices with a device size below one inch and 2.5 million pixels. This is a 100- to 1,000-times improvement compared to existing self-emissive microdisplays, with very good power efficiency. The technology also will allow fabrication of very compact products that significantly reduce system-integration constraints.
SOURCE: CEA-LETI; http://www.leti.fr/en/Press/Press-releases
This article was originally published on 6/3/2015