Until now,the optical characteristics of poly-silicon have not been researched and utilized.In order to solve this pr oblem,the PIN-LED is designed and fabricated in the commercial standard 0.18μ m CMOS process which is offered by United Microelectronics Corporation (UMC) wit hout any modification.Experimental results suggest that the forward and reverse breakdown voltages of the device,whose width of i region is 10μm,are 1.5V and 8.8V respectively.The spectrum ranges from 950nm to 1250n m (the infrared band) when it works at the positive carriers injection mode,whil e ranging from 650nm to 1000nm (the visible light band) at the reverse avalanche breakdown mode.It includes three peaks in the infrared ban d,the wavelengths of the two main peaks are λ＝ 1110nm (E＝1.12eV) and λ＝ 1150nm (E＝1.08eV),re spectively,and the wavelength of the secondary peak is λ＝1050nm (E＝1.18eV).And there is only one main peak in the visible light band,whose wavelength is 730－780nm (1.59－1．70eV).It is confirmed that the PIN-LED made by poly-silicon mate r ials and the LED made by mono-crystalline materials have similar electrical and optical properties,after comparing the above experimental data with the mono-c rystalline′s I-V characteristics and spectra which h ave already been reported.