Rare Earth-Doped Porous Si Infrared LEDs for High-Speed Fiber-Optic Communications

This program has demonstrated intense 1.54 microns PL emission from Er-implanted porous silicon Erp-Si up to temperatures as high as 475K. Intensity of Er emission was about 8 of the PL intensity of a highly doped In0.53Ga0.47As grown on InP. The full width at half maximum of the 1.54 microns PL peak is 40cm. Er was implanted using a commercial implanter operating at 200 keV. The emission characteristics of Erp-Si samples has been extensively studied including temperature dependence, time decay, excitation power dependence, excitation wavelength dependence and correlation between visible and IR emission. There is a strong correlation between the visible PL emission from p-Si host and the 1.54 microns PL emission from Er in p-Si. P-Si samples that exhibited a visible PL spectrum with peak near 750 nm before or after Er implantation resulted in the strongest 1.54 microns PL emission. Nearly identical PLE spectra measured for the Er-related 1.54 mirons emission and the p-Si related visible emission provide the first experimental evidence that Er3 ions are confined in Si nanocrystallites of p-Si. A reduction in 1.54 microns PL intensity of less than a factor of two was observed over 9 to 300K temperature range. Our results indicate that p-Si is an excellent host for 1.54 microns emission. However, in order to make practical devices, one must first develop a process to fabricate porous layer reproducibly and uniformly.