Back-illuminated near-infrared detectors were designed and fabricated using p-InGaAs/p-InP/i-InGaAs/n-InP p-i-n layer structure.In order to optimize the detector layer structure,the device was simulated by drift-diffusion simulator “SimWindows” first,and then the epitaxy material was grown by metal organic chemical vapor deposition(MOCVD).The current-voltage characteristics of the fabricated detectors with and without light were investigated respectively.The results show that the responsivity of the detectors is around 0.7 A/W,and the dark current is about 1?0-4 A/cm2 at reverse bias 0.1V,both of which can fit the simulated results.those values are also comparable to the recently reported result..Our results also show the smaller detector has better dark current density,and the dominated mechanisms of dark current are discussed in the paper.We believe that with the size of device further shrinking,the dark current could be reduced to lower level.