The photoluminescence properties of rare earth doped silicon were investigated with ion beam technique.
The lens-less device is called a Planar Fourier Capture Array. It’s a flat piece of doped silicon.
Practice for conversion between resistivity and dopant density for boron-doped and phosphorus-doped silicon
Test method for thickness of lightly doped silicon epitaxial layers on heavily doped silicon substrates by infrared reflectance