Graphene used to grow the world's smallest microLEDs and highest-density microLED arrays

Researchers from MIT, in collaboration with researchers from other Universities in the US and Korea, have used graphene (and hBN) to develop full-color vertically-stacked microLEDs  - that achieve the highest array density (5100 PPI) and the smallest size (4 µm) reported to date.

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The researchers developed a 2D-materials based layer transfer (2DLT) technique - that involves growing the LEDs on 2D material-coated substrates, removing the LEDs, and then sttacking them. For the red LEDs, the researchers used graphene, coated on a GaAs wafer, while for the green and blue LEDs, they used hBN on sapphire wafers. The graphene red LEDs were transferred using remote epitaxy, while the hBN blue and green ones were removed using Van der Waals epitaxy.