Infrared radiance and temperature measurements on the mesa side of Gunn diodes

Radiance and temperature profiles for the first time have been measured along the mesa side of Gunn diode samples, using an infrared microscope with a spatial resolution of 2.5 mum. Bulk heat generation occurs in the transit region, but measurements have shown a small amount of additional ohmic heating in the substrate layer, which will influence the maximum temperature of the device. The presented thermal measurements have been used to improve the existing thermal finite-element model of the diode. The measurements also represent an alternative method to obtain a more accurate temperature of the diode top contact without coating the sample with a high emissivity layer.