A watt-class 368 nm ultraviolet-A light-emitting diode (UVA LED) grown on Si substrate has been successfully demonstrated. By introducing a polarization-doped electron blocking layer (EBL) featuring graded Al composition (decreasing from 38% to 28%), the energy barrier for electron leakage was significantly raised. This modification led to a marked increase in hole concentration in the active region. After removing the Si substrate and fabricating the thin-film flip-chip LEDs, a 368 nm emission output power of 1015 mW was achieved under 500 mA, corresponding to an external quantum efficiency (EQE) of 60.3% and a wall-plug efficiency of 54.6%. Moreover, the device maintains a high EQE of 54.1% even at a high current density of 164 A·cm -2 , representing an absolute efficiency drop of only 6.2%. The as-fabricated UVA LED also exhibits excellent reliability with over 92% of its initial power after 1,000 hours of aging testing. This work represents a significant step toward the industrial application of high-power UVA-LEDs grown on Si.
Sun et al. (Mon,) studied this question.