This visualization shows the formation and growth of multiple octahedral microcrystals during the photochemical etching of n-type GaAs. Here, we placed a camera in the conjugate plane of the digital projector photochemical etching setup to observe the surface of the sample while the etching is in progress. Images were captured at 26 frames per second and averaged for 1 second. The video is being re-played at 30x speed. For the etching, we used 4:1:80 H2SO4: H2O2: H2O and the light that was projected was a 600 micron large white circle. The etching was done for 20 minutes. The circle appears to shrink in size with time because as the etching proceeds, the edges of the circle do not remain flat and thus light does not get reflected vertically. The microcrystals are the blackish blobs that grow in size, eventually forming into diamond-like shapes
