Phosphor-Free White Light From InGaN Blue and Green Light-Emitting Diode Chips Covered With Semiconductor-Conversion AlGaInP Epilayer

A phosphor-free white lamp was fabricated using the InGaN-based blue and green light-emitting diode (LED) chips covered with semiconductor-conversion layer AlGalnP. The lamp can provide three bands: a 460-nm blue emission coming from the blue LED, a 555-nm green emission coming from the green LED, and 630-nm red emission coming from the excited AlGalnP epilayer. As 50 mA was injected into the white lamp at room temperature, the chromaticity coordinates and correlated color temperature (T_C) are (0.338,0.335) and 5348 K, respectively. By separating injection current into blue and green LED chips, T_C of lamp can be tuned from about 4000 K to 5400 K.