Measurement of the absorption coefficient for light laterally propagating in light-emitting diode structures with In0.2Ga0.8N/GaN quantum wells

A procedure for measuring the absorption coefficient for light propagating parallel to the surface of a GaN-based light emitting diode chip on a sapphire substrate is suggested. The procedure implies the study of emission from one end face of the chip as the opposite end face is illuminated with a light emitting diode. The absorption coefficient is calculated from the ratio between the intensities of emission emerging from the end faces of the sapphire substrate and the epitaxial layer. From the measurements for chips based on p -GaN/In 0.2 Ga 0.8 N/ n -GaN structures, the lateral absorption coefficient is determined at a level of (23 ± 3)cm −1 at a wavelength of 465 nm. Possible causes for the discrepancy between the absorption coefficients determined in the study and those reported previously are analyzed.