A small projector uses an ultra-dense array of gallium nitride (GaN) LEDs. However, epitaxial growth of GaN typically produces a GaN region that is Sum or thicker. To achieve high pixel density, the LEDs have small area, so the resulting LED structures are tall and skinny. This is undesirable because it makes further processing more difficult and has higher optical losses. As a result, it is beneficial to reduce the thickness of the GaN region. In one approach, a wafer with the GaN region on substrate is bonded to a backplane wafer containing LED driver circuits. The substrate is then separated from the GaN region, exposing a buffer layer of the GaN region. The GaN region is thinned and then patterned into individual LEDs. Typically, the buffer layer is removed entirely.