Superconductivity and transport properties of narrow-gap semiconductor Pb(Tl)Te film by HWE growth

The IV-VI semiconductor PbTe doped with a small amount of Tl shows superconductivity of T(c max)similar to 1.4 K in spite of the small hole carrier densities of p similar to 10(20) cm(-3). The superconducting generating mechanism has received much attention from the viewpoint of carrier resonance scattering with a Tl quasi-localized state. In order to investigate the superconductivity on well-defined film samples, we prepared high-quality Pb(Tl)Te films by the HWE method, and carried out the observation of superconductivity and electrical-transport properties. Furthermore, in the experiment with the coordinated system of Pb(Tl,Na)Te film, the results show for the first time the possible existence of two quasi-localized states of Tl causing strong scattering of carriers accompanied by reduction in Hall mobility mu, which play an important role in the superconductivity of this Pb(Tl)Te system.