We report a room temperature operating InAs quantum-dot infrared photodetector grown on InP substrate. The self-assembled InAs quantum dots and the device structure were grown by low-pressure metalorganic chemical vapor depositon. The detectivity was 2.8 × 10 11 cmHz 1/2/W at 120 K and a bias of -5 V with a peak detection wavelength around 4.1 μm and a quantum efficiency of 35 %. Due to the low dark current and high responsivity, a clear photoresponse has been observed at room temperature, which gives a detectivity of 6.7 × 10 7cmHz 1/2/W. A 320 × 256 middle wavelength infrared focal plane array operating at temperatures up to 200 K was also fabricated based on this kind of a device. The focal plane array had 34 mA/W responsivity, 1.1 % conversion efficiency, and noise equivalent temperature difference of 344 mK at 120 K operating temperature.