Absolute internal quantum efficiency of an InGaN/GaN quantum well

Summary form only given. Gallium nitride materials and alloys are fast becoming important semiconductors as blue and UV light emitters due to their wide band-gaps. Applications for highly efficient blue LEDs and UV lasers include large full-color flat panel displays and high-density optical data storage. We report what we believe to be the first measurement of the absolute internal luminescence quantum efficiency of an InGaN/GaN single quantum well. The absolute external luminescence efficiency is calibrated with respect to a perfect 100 % Lambertian reflector. In addition, a correction factor must be used due to the difference between the PL and the pump wavelength. The final step is then to obtain the internal efficiency of the quantum well from the calibrated external efficiency. We use the "photonic gas model", which requires that we model losses in the semiconductor due to reflections from the air-GaN interface, absorption in the cap layer and quantum well, and solid angle for the photon escape cone. Measurements included both luminescence due to the band-to-band transitions and luminescence due to all transitions. Results indicate that the band-edge luminescence internal efficiency is as high as 27% and the luminescence internal efficiency for the full spectral range is as high as 31% for high intensity optical pumping. We have thus developed a technique to make accurate measurements of absolute internal luminescence efficiencies for the GaN materials and alloys.