Photoluminescence of Layered Semiconductor Materials for Emission-Color Conversion of Blue Micro Light-Emitting Diode (µLED)

A micro light-emitting diode (μLED) is a key device for the future of advanced information. Owing to expand its application widely, the concept of the emission-color conversion using layered semiconductors as a color converter is proposed. In addition, it is demonstrated that layered semiconductors were transferred directly onto μLED chips, and the emission-color conversion is realized. The layered GaS1−xSex alloy, whose energy bandgap can be controlled by tuning the S and Se compositions, was selected as a color converter. The photoluminescence (PL) measurements using a blue LED as an excitation source revealed that GaS0.65Se0.35 and GaSe can show green and red luminescence with center energies of 2.34 and 1.94 eV, respectively. The emission color of gallium nitride (GaN)-based blue μLEDs covered with GaS0.65Se0.35 and GaSe thin films were clearly converted to green and red, respectively. Furthermore, the emission color could be controlled by changing the film thickness. Thus, these results suggest the possibility of emission-color conversion of blue μLED chips utilizing layered materials.