A low temperature (50 degrees C) thin oxide passivation layer has been employed to substantially suppress the dark current of SiGe planar metal-semiconductor-metal photodetectors (MSM-PDs). The low temperature oxide layer was prepared by using liquid phase deposition (LPD) process and deposited in regions between the interdigitated electrodes of MSM-PDs. A four time improvement in the dark current of the passivated SiGe device was achieved. The introduction of LPD-oxide passivation layer is believed to suppress surface states situated on SiGe surface and therefore reduce surface leakage. Additionally, such a thin oxide (15 nm) passivation layer did not affect the optical performance of passivated MSM-PDs. (c) 2006 Elsevier B.V. All rights reserved.