Fig. 1. Near-field simultaneous measurement method of electroluminescence spectrum and in-situ temperature based on QD fiber probes. (a) Schematic of electroluminescence spectrum and in-situ temperature simultaneous measurement system of GaN sample based on QD fiber probes; (b) temperature dependent fluorescence spectra of QDs excited by 532 nm laser; (c) calibration curve of fluorescence spectrum center peak position as a function of temperature

Fig. 2. GaN sample and its surface morphology. (a) Schematic of GaN sample; (b) optical image of GaN sample under 20× objective lens; (c) line-scanning height distribution of GaN sample with atomic force scanning height image in 100 μm×50 μm region shown in inset

Fig. 3. Electroluminescence spectra and volt-ampere characteristic of GaN samples. (a) Electroluminescence spectra collected by QD fiber probes in near field of GaN at different excitation voltages; (b) volt-ampere characteristic curve of GaN

Fig. 4. Effect of GaN electroluminescence on temperature measurement by QD fluorescence. (a) QD fluorescence spectrum excited by GaN electroluminescence under 12 V voltage excitation is compared with QD fluorescence spectrum directly excited by 532 nm laser ; (b) magnified result of dashed box in Fig. 4 (a)

Fig. 5. In-situ temperature measurement of GaN samples. (a) Power and surface local temperature rise of GaN under different excitation voltages; (b) comparison of temperature rise at GaN and electrode under power-on and power-off conditions