Improved internal quantum efficiencies of far-UVC AlGaN/AlN quantum wells by the use of semipolar r-planes

We investigate the internal quantum efficiencies (IQEs) of AlGaN/AlN quantum wells (QWs) on (0001) c- and semipolar (1 1 ¯02) r-planes in the far-ultraviolet C (far-UVC) region using time-integrated photoluminescence and time-resolved PL spectroscopies. Stronger emissions from r-QWs are observed, especially at shorter wavelengths, indicating that the r-QWs exhibit higher IQEs than the c-QWs. Analyses of the experimental results suggest that the main reason for the higher IQEs of r-QWs in the far-UVC region is shorter radiative lifetimes and an increase in a slow decay component, which might be related to a reduction in the number of nonradiative recombination centers. These findings indicate the superiority of the semipolar r-plane for fabricating QWs that emit in the far-UVC region.