Phosphor-free white light-emitting diode using InGaN/GaN multiple quantum wells grown on microfacets

We demonstrate phosphor-free light-emitting diode (LED) by growing InGaN/GaN multiple quantum wells (MQWs) on the n-GaN microfacets. The white emission was realized by combining emissions from InGaN/GaN MQWs grown on c-plane (0001), semipolar {11-22} and {11-10} facets which are selectively grown on n-GaN with trapezoidal shape arrays. The photoluminescence (PL) and electroluminescence (EL) measurement revealed that the long wavelength light was emitted from InGaN/GaN MQWs grown on c-plane (0001), while the short wavelength light was emitted from that of semipolar microfacets. The change in the emission wavelengths from each microfacets was due to the difference in the well thickness and In composition of each MQWs. The LED showed white emission at an injection current between 180 and 230 mA. These results suggested that white emission is possible without using the phosphor by combining emission lights emitted from microfacets.