A novel method for fabricating low cost Si-based continuously tunable long wavelength resonant cavity enhanced (RCE) photodetectors was reported,in which InGaAs epitaxy layers were bonded to silicon substrates without any special treatment on bonding surfaces,employing the silicate gel as bonding medium.A thermally tunable Si-based InGaAs RCE photodetector operating at 1.3~1.6 μm was obtained,with a quantum efficiency of about 44% at the resonant wavelength of about 1.5 μm and a FWHM of about 12.5 nm.A tuning range of 14.5 nm and a 3 dB bandwidth of 1.8 GHz were obtained. This device was fabricated with traditional processes,thus the cost was decreased. It demonstrates a great potential for industry processes.