Fabrication of Less Bowed Light-Emitting Diodes on Sapphire Substrates with a SiO2 Thin Film on Their Back Sides

Abstract

In this study, less bowed light-emitting diodes (LEDs) were fabricated by preparing a LED structure on a sapphire substrate with a SiO2 thin film on its back side. The SiO2 thin film with a low thermal expansion coefficient reduced the bow of the wafer generated by the thermal expansion coefficient difference. As the thickness of SiO2 was increased from 1 μm to 4 μm, the compressive stress in the GaN film was reduced from 16% to 62% with respect to that without SiO2 thin film. The stress reduction in multiple quantum wells also enhanced the internal quantum efficiency of the LED by reducing the piezoelectric field.