Researchers at the Fraunhofer Institute for Laser Technology (ILT) have developed an optical technique to study the structural and electronic properties of gallium nitride (GaN) and GaN composites at a nanometre scale.
The inspection technology could improve understanding of gallium nitride layers, which form the basis for blue LEDs. This year’s Nobel Prize in Physics was award to the Japanese researchers who were the first to produce high-quality gallium nitride layers and put them into series production in 1993.
In collaboration with fellow researchers from the Chair for Experimental Physics at RWTH Aachen University, scientists from Fraunhofer ILT have developed an innovative, broadband tunable laser system that is geared toward the particular requirements of semiconductor analysis. Wavelength can be adjusted to the material under inspection, which enables the new system to investigate a wide range of materials. It has also opened up access to materials that were beyond the capacities of previous systems, including GaN and GaN composites.
Using the new analysis system, last year the researchers in Aachen were able to obtain an optical 2D image showing tensions in the crystal structure of undoped GaN wafers for the first time. Computer simulations helped quantify the exact extent of the tension. Recently the technique was also applied to a variety of doped GaN layers within complex structures. It’s the first time an optical technique has been available to study the structural and electronic properties of GaN and GaN composites at the nanometre scale.