We previously demonstrated that despite the low electrical to optical conversion efficiency of single crystal silicon, variety of practical two three and multi terminal single crystal silicon light emitting devices (SiLEDs) can be fabricated  using only conventional IC design rules and device processing.

Their action is based on reversed biased silicon PN junctions operated at the charge ionization mode which result light emission that can be seen through optical microscope. In shallow junctions the light seems to be emitted from continues area(s) at the junction's upper surface. However, at low reverse currents and higher magnifications it becomes evident that the light is emitted from many microscopically small isolated spots of various random shapes and sizes. As the reverse current is increased, their dimensions grow, their emission intensity increases, and new smaller light emitting spots appear. As the current further increased, they seem to coalesce, giving rise to an appearance of continues-like light emitting area(s).

Each microscopic light emitting spot is termed "microplasma". The light emitted from a microplasma results from a high density of high energy excess carriers which are generated at the high electric field in the junction's depletion region. Depending on the junction's doping levels, the excess carriers are created as a result of ionization process of either (a) avalanche process that creates charge multiplication by impact ionization, or (b) field emission ionization, or their combination. The excess carriers perform quantum transitions to the lower energy levels, resulting light generation and emission.

Here, a model is proposed for only one operational aspect, i.e, the affect of the microplasms properties on the emitted light spectrum. A microplasma is located at a crystal defect which usually contains higher doping concentration then the rest of the junction. This defect is associated with local pressure that locally distorts the lattice structure and therefore locally distorts the energy band structure there. As a result, a higher current density flows at the location where a bandgap narrowing and higher conductivity (doping) exists, with respect to the rest of the junction area. This is a preferable location for charge ionization and excess carriers generation, which results local light emitting quantum transitions. These locations are viewed on the junction surface as light emitting microscopic microplasmas spots. Since each defect is differently distorted its local bandgap narrowing is different than that of the other defects. Accordingly, the wavelengths of the light emitted from them are different, yielding a range of colors (including visible) which affect the overall radiation spectrum emitted from the junction area  ranging from 350nm to 850nm and peaking at about 650nm.