Optical pump-and-probe measurement of the thermal conductivity of nitride thin films

We report on measurements of the thermal conductivity of epitaxially grown nitride thin films. These semiconductor materials are of considerable technological importance for applications such as blue-light emitters and high-power, high frequency electronic devices. Measurements were made in the temperature range of 150–400 K using an optical technique in which the sample is heated with an ultrashort (∼150 fs) light pulse, and a time-delayed probe light pulse is used to measure the temperature of the sample as a function of time. The conductivity of the polycrystalline sample and the alloys are found to be significantly reduced compared to published values for bulk GaN.