Characteristics of a Non-Phosphor White LED Grown by Using Mixed-Source HVPE

The growth of an AlGaN-based non-phosphor white light emitting diode (LED) on a templated n-GaN (0001) sapphire substrate is performed by using mixed-source hydride vapor phase epitaxy (HVPE) with a multi-sliding boat. The DH (doublehetero) structure is grown by using a selective area growth (SAG) method. The non-phosphor white LED structure consists of a Te-doped AlGaN cladding layer, an AlGaN active layer, a Mg-doped AlGaN cladding layer and a Mg-doped GaN capping layer. The gas flow rates of HCl and NH3 are maintained at 20 seem and 800 sccm, respectively. The growth temperatures of the source zone and the growth zone axe 900 degrees C and 1090 degrees C respectively. The electroluminescence (EL) main peak of the AlGaN-based white LED is observed at 400 nm and minor peaks are emitted in a broad spectrum from 450 nm to 600 nm. A combination of blue and broadband yellow peaks creates a white light. The non-phosphor white LED has a measured color rendering index (CRI) from 76 to 87. These results show mixed-source HVPE with a multi-sliding boat can be used to fabricate a non-phosphor white LED. Additionally, optical module measurements and X-ray diffraction (XRD) verified the optical and the crystal quality of the white LED.