Characteristics of gallium doped silicon infrared detectors

Data on lifetime, responsivity, noise and detectivity has been obtained on discrete Si:Ga infrared detectors as a function of temperature (5K - 35K), background photon flux density ( photons/cm²-sec) and bias field (E = 200-1200 v/cm). Several detectors with differing boron impurities and compensation were evaluated. The effects of compensation on the amplitude of the photoconductive lifetime, responsivity and noise is demonstrated with experimental data. From the data, the quantum efficiency of the detectors is shown to vary from 0. 25 to 0.4. A theoretical model has been developed to explain the observed behavior of the lifetime, signal, noise and detectivity. The model is based on solving the rate equations for the excess carriers for a three impurity level model (i. e. , phosphorus, boron and gallium levels). The theory is compared with the experimental data obtained on the detectors showing correlation. Impulse response data on the Si:Ga detectors was obtained using a PbSnTe laser.