Efficient temperature sensing using photoluminescence of Er/Yb implanted GaN thin films

The luminescence characteristics of GaN films implanted with Er at low doses were evaluated. The defect-related yellow luminescence (YL) and green luminescence (GL) bands observed under direct excitation with 488nm were attributed to the transitions via different charge levels of the same defect. The quenching behavior of the luminescence intensity either with the temperature or concentration variation can be attributed to nonradiative energy transfer (ET) and/or charge transfer by trapping impurities. The temperature dependence of the YL band allowed us to identify the defect responsible for this emission. The best candidate for this defect was found to be a nitrogen-vacancy. A GaN sample co-doped with Er3+ and Yb3+ ions was prepared, and its optical properties were analyzed. The incorporation of Yb3+ improved the PL emission intensity in the visible region. This feature results from the efficient ET processes between these two doping ions. The color coordinate analysis indicates that Er3+/Yb3+ co-doped GaN semiconductor emits light with color in the white-light region. To investigate the temperature sensing application of the synthesized co-doped semiconductor, the temperature-sensing performance was evaluated using the fluorescence intensity ratio technique in the temperature range 200-300K. The significant temperature sensitivity indicates its potential as a temperature sensing probe. The maximum sensitivity was 15×10-4K-1 at 200K.