In recent years ion implantation has been used to develop MCT and other infrared photovoltaic detectors, However, the implanted ions usually have a nonuniform depth profile in the implanted layer, with the typical depth less than lμm, within which the concentration of the implanted species may change over 3 to 4 orders. Thus within the layer there is an electric field outside the space-charge region. The electric field can be estimated with its intensity as high as 1x102-1x103v/am at 77k. In the present work the effect of the electric field is studied to show its way to effect the performance of the infrared photovoltaic detectors.
Using the formulae obtained in this work, the RoA, product, responsibility, noise and detectivity of n-on-p Hgo.8Cd0.2Te photovoltaic detector operating at 77k are calculated for 300k backgrond and 27πfield of view. The results show that they are all related to the electric field in the implanted layer. It is interesting that when the electric field direct to the surface of n-region, namely negative field, the RoAlv=0 product contributed by n-region can not be neglected and the responsibility R,. and detectivity Dℓ, decrease. In the case of positive electric field, responsibility RA and the noise Vn both increase while the Dℓ increases slightly.
Our calculation suggests that the proper technology process should be taken in manufacturing the MCT n-on-p infrared photovoltaic detector by use of ion implantation to eliminate the negative field in the n-region in order to avoid the harmful effect. The calculation is performed to show how the electric field in the ion implanted layer on Hg0.8Cd0.2Te to effect the performance of Hg0.8Cd0.2,Te photovoltaic detectors. The result shows that a reverse electric field is unfavorable for the performance of the photovoltaic detectors.