Volume-nonequilibrium states in Pb1-xSnxTe(In)

Static voltampere characteristics and conductivity distribution in high-ohmic at 4.2 K monocrystals Pb0.25Te+0.5 at % In with indium contact grid during light and electrothermal local excitations of the system have been investigated. Measurements have been carried out by IBM RS computer equipped with analogue-to-digital conversion unit and 16-channel analogue commutator. It is discovered that under local short-term irradiation of a crystal with IR radiation from a thermal source with temperature of ∼20 K long-lived volume-nonequilibrium states with abruptly (up to 4 orders) different conductivity arise. It is established that in electric field gradient reversible or irreversible 'drawings' of nonequilibrium electrons into nonconducting areas occur. Appearance of the indicated states results in a new effect-photoelectrothermal instability on local Joule heating of a crystal revealing in giant stimulation of conductivity between 'point' contacts by means of electric field