InGaAs/InP single-photon avalanche photodiodes (SPADs) is capable of detecting single-photon in the near-infrared spectrum for applications such as quantum communication, fluorescence lifetime imaging, and Light detection and ranging(LIDAR). The effect of multiplication layer width on the performance of SPADs in both linear and Geiger mode have been theoretically studied. Three-types of InGaAs/InP planer SPADs with different multiplication width are fabricated and evaluated. The results of this study suggest that modifying the width of the multiplication layer can regulate the breakdown voltage, punch-through voltage, and dark current of the device. It is found that the measured time jitter is decreasing with the reduction of the width of the multiplication region. These characteristics can be used to optimize the temporal resolution of SPADs device. © 1965-2012 IEEE.