Abstract
Unintentionally doped n-type GaN(0001) epitaxial layers grown by metal-organic chemical vapor deposition (MOCVD) on sapphire substrates have been irradiated with 75 MeV Tin (Sn5+) ion. Effect of different ion fluences at 1011, 1012 and 1013 cm-2 were studied by means of time correlated single photon counting (TCSPC), UV-visible optical spectroscopy and photoluminescence (PL) measurements at room temperature. The exponential decay of minority carrier life times was observed between 1910 and 1110 ps (pico-second) with increasing ion doses upto 1013 cm-2. High-energy irradiation with different ion fluences of GaN epitaxial layers creates midgap states in the material. Change in the absorption edges between 3.41 and 2.95 eV were observed by UV-absorption coefficient (α2) method on increasing fluences rate. Band-edge and yellow emissions were recorded for all GaN samples by transient steady state PL measurement at room temperature.