In 2013, Ye et al. have a publication of "Thermal Transient Effect and Improved Junction Temperature Measurement Method in High Voltage Light-Emitting Diodes". In their experiments, a high voltage LED chip was directly attached on silicon substrate with thin thermal interface material (TIM). The temperature sensors were fabricated using standard silicon processing technologies which were calibrated ranging from 30 °C to 150 °C. The thickness of the chip and TIM were 153μm and 59μm, respectively. Thus the sensors were very close to the p-n junction. The silicon substrate was positioned and vacuumed on a cumbersome thermal plate with accurate temperature controller in an enclosure. The experimenters applied step-up/step-down currents and measured the characteristics between temperature and forward voltage after 100 ms. In this work, the ‘recovery time’ is defined as the interval from the start of power change to the time at which the temperature became again equal to the initial temperature value. The results show that the junction temperature of LED decreases significantly and immediately (more than 10 °C) when a current from 100 μA to 15 mA is applied. Then, the junction temperature gradually increases. After a recovery time of ~100 ms, the junction temperature reaches the initial value. At the steady state of 15 mA, the applied high current is instantly reduced through a step-down mode to 100 μA. The measured junction temperature increases by 4 °C within 0.1 ms. The sensor temperature simultaneously shows a temperature increase of 2 °C. Subsequently, the junction temperature gradually decreases. After a recovery time of ~100 ms, the junction temperature decrease to their initial values. Then the junction temperature continues to decrease until the system achieves the steady state at room temperature. Notably, the junction temperature changes in opposition to the current change in the chips.