Study of Thermal Boundary Resistance in Light Emitting Diodes

The one-dimensional heat flow dynamics in a light-emitting diode (LED) in the vertical direction can be effectively described by the thermal conduction laws proposed by Fourier. With suitable boundary conditions that meet the operating requirements of LEDs, the solutions of Fourier thermal conduction laws are applicable to analyze the thermal properties of the devices and the substrates such as thermal conductivity, heat capacitance, and thermal resistance. However, the heat transfer in materials relies on phonon transport, and phonons might be scattered by boundaries, micro-structures and dislocations in devices, the real heat transport dynamics in currently used LEDs, in which plenty of interfaces exist, could be far more complicated than the explicit solutions. Especially for nitride LED, due to the large lattice mismatch, the thermal boundary resistance easily to reveal in this situation. The purposes of this project are to realize how the effects of the unavoidable interfaces and microstructures on the heat transport in devices and analytical solutions of thermal conduction. The results are expected to be able to improve the thermal properties of high-power LEDs. There are several innovative point, first point is to estimate thermal boundary resistance with only electronically measurements, and second point is by measuring temperature difference across DBR which using transient electroluminescence measurement Therefore, the project is not only valuable for thermal conduction engineering for high-power LEDs but also offers a new direction for studying nano-science concerning the physics of phonon transport.

Project ID:PB9807-2590
External Project ID:NSC98-2221-E182-005