A dependency of emission efficiency of poly-silicon light-emitting device on avalanching current

Abstract

A novel polysilicon light emitting device (LED) was realized in a standard complementary metal oxide semiconductor (CMOS) process that is based on a p-n junction reverse bias configuration. This LED can emit visible light based on the reverse bias p-n junctions in the dark. The central emitting doped structure element of this LED is n+-p-n+-p-n+ stacked layout, which is similar to two reverse bias p-n junctions and two forward bias p-n junctions connected in series. The device mechanism for the visible light emitting process is defined by means of an avalanche breakdown process that occurs between the highly doped n+ region and the lightly doped p region in the reverse bias p-n junctions. By using hot carriers generated in avalanche process, the emission spectrum from the device exhibits a wide spectrum whose wavelength range is from 400 nm to 900 nm at an operating voltage of 16 V. We compare the designed light intensities at the different wavelengths in other to obtain the dependency of the light emission at various wavelengths under different currents conditions. From the experimental observations, and based on the calculation of the quantum efficiency and power conversion efficiencies as related to the light emission, we confirmed that this particular LED has a better efficiency than three-terminal gated diode. The silicon light source could find some applications in on-chip optical interconnect and in electro-optical conversions in future all-silicon integrated photonic circuitry.