Researchers pioneer stacking of micro-LEDs – Zoo House News

Put on a virtual reality headset and chances are it’ll seem like you’re seeing the world through a screen door. Current flat panel displays use pixels that are visible to the naked eye, along with small unlit dark spaces between each pixel that can appear as a black, web-like grid.

Now researchers at the Georgia Institute of Technology, in collaboration with researchers at the Massachusetts Institute of Technology (MIT), have developed a new process based on 2D materials to create LED displays with smaller and thinner pixels. Enabled by two-dimensional, material-based layered transfer technology, the innovation promises a future with clearer and more realistic LED displays.

The team published an article entitled “Vertical full-colour micro-LEDs via 2D materials-based layer transfer” in Nature journal in February. Co-authors also include researchers from Sejong University in Korea and other institutions in the US and South Korea.

Georgia Tech Europe professor Abdallah Ougazzaden and research scientist Suresh Sundaram (both of whom also hold appointments at Georgia Tech’s School of Electrical and Computer Engineering) worked with researchers at MIT to literally turn the traditional LED manufacturing process on its head. Instead of using dominant processes based on juxtaposing red, green, and blue (RGB) LEDs, which limits pixel density, the team stacked vertically free-standing, ultra-thin RGB LED membranes, achieving an array density of 5,100 pixels per inches – the smallest pixel size reported to date (4 microns) and the smallest stack height ever – all while delivering a full commercial color gamut. This ultra-small vertical stack was achieved by the technology of van der Waals epitaxy on 2D boron nitride developed at the Georgia Tech-Europe laboratory and the technology of remote epitaxy on graphene developed at MIT.

The study showed that the world’s thinnest and smallest pixel displays can be enabled through active layer separation technology using 2D materials such as graphene and boron to enable high array density micro-LEDs, resulting in full-color realization of micro- LED displays leads.

A unique facet of the two-dimensional, material-based layer transfer technology (2DLT) is that it enables the reuse of epitaxial wafers. Reusing this expensive substrate could significantly reduce the cost of producing smaller, thinner, and more realistic displays.

“We have now demonstrated that this advanced 2D material-based growth and transfer technology can outperform traditional growth and transfer technologies in specific areas, such as virtual and augmented reality displays,” said Ougazzaden, the lead researcher on the Georgia Tech team .

These advanced techniques were developed in metal-organic chemical vapor deposition (MOCVD) reactors, the key tool for wafer-scale LED production. The 2DLT technique can be replicated on an industrial scale with high throughput yields. The technology has the potential to take the field of virtual and augmented reality to the next level, enabling the next generation of immersive, realistic micro-LED displays.

“This emerging technology has tremendous potential for flexible electronics and heterogeneous integration in optoelectronics, which we believe will develop new functionalities and attract industry to develop commercial products from smartphone screens to medical devices,” said Ougazzaden.