Phosphor-Free Monolithic White-Light LED

Phosphor-free monolithic InGaN-based white-light LED has the advantages of simpler device process and potentially higher efficiency. Several techniques have been developed for implementing such white-light LEDs. Among them, the key issue is the growth of a high-quality high-indium InGaN/GaN quantum well (QW). An underlying InGaN layer growth technique is introduced for enhancing the crystal quality of a high-indium QW. To demonstrate the superior properties of a QW grown with this technique, a green LED is fabricated based on the underlying growth technique to compare with another LED of the same emission wavelength based on the conventional growth method. Then, the underlying growth technique is used to grow three yellow-emitting QWs of high efficiency. The yellow photons mix with blue light from an overgrown blue-emitting QW to produce white light. The improved properties of the phosphor-free monolithic white-light LED are discussed in detail.