Indium-gallium nitride (InGaN) is a semiconductor alloy that is used for constructing blue and green light emitting diodes (LEDs). When doing research on InGaN, the crystals are sometimes probed by irradiation with a beam of electrons in a scanning electron microscope. This image shows a small crystal cluster that accidentally grew during the w:MOVPE process. The lightness corresponds to its standard w:SEM image, whereas the color overlays were added according to the light emitted under the electron beam. Blue and green channels are roughly natural colors, while red encodes the ultraviolet emission. The image demonstrates that InGaN/GaN structures are highly anisotropic, and so are their cathodoluminescence properties.
Image taken in the Institute of Physics, Czech Academy of Sciences, using Philips XL30 ESEM equipped with custom color-resolved cathodoluminescence photomultiplier setup. Author acknowledges the great help of R. Horešovksý.