Development of High-Quality SAM on Sapphire Pseudosubstrate by SPE for Long-Wavelength LEDs

One of the main challenges in achieving long-wavelength InGaN-based emitters is their large lattice mismatch, around 11% between InN and GaN. ScAlMgO4 (SAM) is lattice-matched with In0.17Ga0.83N, which allows the growth of high indium composition InGaN films with good quality. Using solid-phase epitaxy (SPE) of SAM on a sapphire substrate, SAM films can be achieved at any wafer size with greatly reduced cost while keeping their lattice-matched properties. In this work, we have achieved smooth InGaN films grown on SAM on sapphire with similar morphology as InGaN films deposited on free-standing native SAM substrates. Moreover, we have demonstrated the first InGaN-based green LED on SAM on a sapphire substrate with a peak emission wavelength at 525 nm and ∼9 nm of blue shift.