Laser lift-off transfer printing of patterned GaN light-emitting diodes from sapphire to flexible substrates using a Cr/Au laser blocking layer

We develop a method to directly transfer the array of GaN-based light-emitting diodes (LEDs) from sapphire onto flexible substrates by a laser lift-off (LLO) process. Cr/Au layers are employed as a laser blocking layer to protect the supporting polymer layers from the laser beam and sharply separate the LEDs from the sapphire during the LLO process. This method dramatically increases the transfer yield of patterned LEDs up to 95% by decreasing the laser-induced damage in the supporting polymer layers and LEDs.