GaN-Based Light-Emitting Diodes With AlGaN Strain Compensation Buffer Layer

An AlGaN strain compensation layer (SCL) was proposed to modulate the strain and thus alleviate the polarization of GaN-based light-emitting diodes (LEDs). With the SCL, it was found that the 350 mA LED output power could be enhanced from 258 to 285 mW. It was also found that the SCL could alleviate the efficiency droop and reduce the forward voltage of the LEDs. These improvements could all be attributed to in-plane tensile strain induced by the AlGaN layer which could effectively compensate the compressive strain induced by the InGaN well layers. From micro-Raman spectra measurement, it was found that in-plane biaxial stresses in the reference and SCL samples were 0.30 and 0.07 GPa, respectively.