Wafer-scale emission uniformity of InGaN-based red light-emitting diodes on an in situ InGaN decomposition template

Abstract

We propose a strain relaxed template (SRT), which consists of an InGaN decomposition layer (DL) and GaN protecting layers grown at three different temperatures as decomposition stop layers (DSLs), to enhance the indium incorporation in quantum wells. The high-temperature growth of the DSL decomposed the InGaN DL and created voids inside to release the strain of the as-grown templates. Although the surface morphology slightly degraded with the DL-DSL SRT, the emission wavelength over the 4-in. wafer was uniform with a standard deviation of 3.4 nm. In addition, the chip containing DL-DSL SRT exhibited an average redshift of 15 nm in peak wavelength compared to the chip without DL-DSL SRT, and the full widths at half-maximum of all samples were below 55 nm. Finally, we achieved an InGaN red LED chip using the DL-DSL SRT structure, exhibiting a red emission of 634 nm at 10 A/cm2 with an external quantum efficiency of 1.3%. The high-efficiency and uniform emission wavelength across the epi-wafer demonstrate the great potential of inserting a DL-DSL SRT to mass-produce high-performance, long-wavelength InGaN LEDs.