Indium doped lead telluride-based photodetectors have demonstrated extremely high performance of operation in the Terahertz wavelength range at least up to 240 microns. These materials reveal a number of other advantageous features such as "internal" accumulation of the incident radiation flux, high spatial and temporal stability of parameters, high radiation hardness, enhanced quantum efficiency and others.
Specifics of the impurity states in indium-doped lead-tin tellurides allows construction of a special type of "continuous" focal-plane array. Photoexcited free electrons do not diffuse from the region of generation in these materials, therefore spatial distribution of the incident radiation flux reflects in the spatial distribution of concentration of photogenerated free electrons. We report on the experimental confirmation of this statement.
Ideas for the information readout are presented. The first idea is contact readout, when two mutually perpendicular contact sets isolated from each other in every knot are deposited to the sample. The conductivity in the vicinity of every knot can be measured by proper multiplexing of the two sets of contacts. The second idea is readout with an electron beam, when the electron current in every position of the beam would depend on the concentration of photogenerated electrons in this point of a sample. The third idea involves formation of a heterostructure composed of a relatively wide-gap semiconductor and an active indium-doped lead tin telluride layer sandwiched between two semitransparent electrodes. Readout is performed by laser beam scanning. Advantages and disadvantages of all approaches for the readout are discussed.
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