STIMULATED RECOMBINATION FROM THE DEFECT LEVEL IN DOPED LEAD-TELLURIDE

The relaxation processes of the photoexcited carriers from the defect level in the band gap to the valence band states were investigated in Na and Tl doped p-type PbTe single crystals at T = 77 K. The observed photosignal oscillations were proved to be induced by stimulated recombination of photoexcited carriers from the defect level E(d) almost-equal-to 50 meV above the top of the valence band. Non-equilibrium carrier inversion population was produced by impulses of a TEA CO2-laser. The observed stimulated recombination may presumably be used for designing IR semiconductor lasers operating in the wavelength range of lambda approximately 25 mum at T = 77 K.