In 2013, Ye et al. have a publication of "Thermal Transient Effect and Improved Junction Temperature Measurement Method in High Voltage Light-Emitting Diodes".
[4] In their experiments, a high voltage LED chip was directly attached to a silicon substrate with thin thermal interface material (TIM).
The silicon substrate was positioned and vacuumed on a cumbersome thermal plate with an accurate temperature controller in an enclosure.
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.
At the steady state of 15 mA, the applied high current is instantly reduced through a step-down mode to 100 μA.
This chip can withstand a wider range of applied currents and facilitate more precise power change for observing the thermal inductive responses.
The chip package was soldered to a metal core printed circuit board and mounted on a thermal plate with controllable temperatures.
The results are consistent with the previous thermal inductive measurement in the GaN-based high-voltage LED chip.
It was shown that the time derivative of the heat current is proportional to the negative temperature difference across the device, in analogy to an electric inductor where the time derivative of the electric current is proportional to the negative voltage difference.