In this paper, we report silica based planar waveguides doped with Er3+, and co-doped with GeO2 and Al2O3 These sol-gel derived planar waveguides were fabricated on SOS (silica on silicon) using multiple spin-coating and rapid thermal processing (RTP). Investigation has been made on their characteristics in terms of their application in optical amplification and lasing, including photoluminescence (PL), fluorescence lifetime, refractive index, propagation loss, surface roughness, Fourier transform infrared (FTIR) spectrum and X-ray diffraction (XRD) analysis. The propagation loss of a 20-layer planar waveguide was measured to be about 1.6 dB/cm for TE0 and 2.2 dB/cm for TM0 mode. A strong emission transition (I-4(13/2) --> I-4(15/2)) at 1.536 mu m with a lifetime of 3.6 ms has been obtained for an optimized molar composition of 90SiO(2): 10GeO(2): 20AlO(1.5): 1ErO(1.5).