MCP infrafed detectors with close to radiatively limited performance at 240 K in the 3-5 mu m band

Results are reported on infrared photodiodes which have been designed to mi nimize the dark diffusion currents for operating temperatures above 200 K i n the MWIR (3-5 mu m) waveband. It is shown that by adjusting the doping an d composition profiles, the dark currents due to Auger and contact diffusio n mechanisms can be controlled leading to devices which are close to being radiatively limited. The radiatively-generated current has been calculated as a function of temperature from the measured spectral response and this i ndicates that the radiative contribution increases from about 53% at 240 K to 65% at 300 K. In addition, it is shown that these internally-generated r adiative currents can be reduced using negative luminescence. This result i s the first experimental verification that the internally-generated radiati ve mechanism can contribute to the diffusion current.