Active‐Matrix GaN µ‐LED Display Using Oxide Thin‐Film Transistor Backplane and Flip Chip LED Bonding

Abstract A 2 in. active‐matrix light‐emitting diode (AMLED) display by integration of the micro‐LED onto the oxide thin‐film transistor (TFT) backplane using flip chip bonding is reported. A blue‐emitting micro‐LED (µ‐LED) with a size of 90 × 50 µm 2 is fabricated on the GaN epi grown on a sapphire substrate. The amorphous indium‐gallium‐zinc‐oxide (a‐IGZO) TFT on glass exhibiting the mobility of 18.4 cm 2 V −1 s −1 , turn‐on voltage ( V ON ) of 0.2 V, and subthreshold swing 0.25 V dec −1 , is used for LED backplane. A two TFT and one capacitance pixel structure is utilized for driving 128 × 384 AMLED with 120 Hz frame rate. The laser lift‐off process with flip‐chip bond allows the transfer of the µ‐LED chips with 49 152 pixels onto the TFT backplane, demonstrating a 2 in. AMLED display with a good gray scale image. The current efficiency of µ‐LED is found to be 12.9 Cd A −1 at the luminance of 630 Cd m −2 . Therefore, a‐IGZO TFT backplane can be used for µ‐LED displays.