Effect of temperature on relaxation of energized charge carriers in a bismuth point contact

The effect of temperature and conditions of heat removal from a current-carrying point contact on the energy relaxation of electrons injected in it is investigated by the transverse electron focusing (TEF) technique in Bi. A specific phonon structure of the EF peak is formed during the injection of highly nonequilibrium charge carriers with an excess energy ΔE > EF in the region of the current-carrying point contact due to discrete nature of electron relaxation in the point contact, reflecting the energy distribution of electrons injected in the metal. It is found that a decrease in temperature from 4.2 to 1.5 K causes a linear (in temperature) displacement of the observed system of phonon singularities towards stronger magnetic fields, which undergoes a jump corresponding to the transition through the λ-point. The excess energy ΔE of injected electrons is determined not only by the applied voltage, but also by the point-contact temperature and the condition of heat removal from it.

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