One-chip multicolor electroluminescence from an isotype heterojunction light-emitting diode

摘要

Both direct current (DC) and alternating current (AC) driving electroluminescence were obtained from isotype heterojunction (n-i-n: n-ZnO/i-HfO_2-GaN) light-emitting diodes (LEDs) fabricated by a pulsed laser deposition system. The n-ZnO film maintained the same growth orientation as the n-GaN film and was of high crystalline quality even on a polycrystalline high-k HfO_2 thin film. The as-produced n-i-n LEDs can emit strong visible light or dominant ultraviolet light at ～392 nm, depending on the polarity of the applied DC voltages. The individual spectrum under either forward or reverse bias can be integrated to one spectrum by applying 50 Hz AC driving voltages (sinusoidal signals). More importantly, near white-light can be obtained by tuning the symmetric driving AC sinusoidal signals to the asymmetric ones. This simple and facile method only by applying AC asymmetric signals to achieve white light emission on one single chip may provide an easy route for the white-light solid-state lighting industry.