Abstract: The temperature behavior of double-heterostructure In_0.53Ga_0.47As PIN photodetectors at different reverse bias voltages and wide temperature ranges was investigated. Results show that at lower bias voltage the dark currents are dominated by generation-recombination mechanism, whereas at higher bias voltage dominated by tunneling effects （including traps tunneling and band to band tunneling）. The temperature dependence of dark current shows corresponding characteristics. The influence of noise mechanisms on R₀A product is also discussed theoretically, compared with the measured results of fabri- cated devices. Results show that at lower temperature generation-recombination noise mechanism is dominant,while at higher temperature Auger noise mechanisms become dominant.