Properties of Pb1−xEuxTe films prepared by hot-wall epitaxy

Abstract

Pb1−x Eu x Te films were prepared by hot‐wall epitaxy, evaporating PbTe, Eu, and Te from the same quartz‐tube furnace onto BaF2 (111) substrates. Good crystalline films were obtained by preparing the films in excess Te vapor. Dependence of the energyband gaps and lattice constants of the Pb1−x Eu x Te films on the EuTe content was measured through the optical absorption, x‐ray diffraction, and x‐ray microanalysis. Temperature dependence of the energyband gap was also measured. Single‐phase films with E g ≤0.83 eV and x≤0.26 were obtained. Derivatives of the band gap with respect to the EuTe content x(d E g /d x) were 3.5 eV at 300 K and 4.5 eV at 77 K up to x=0.06, and the value decreased for x>0.06. Electrical properties of the Pb1−x Eu x Te films were also measured. Bi and Tl were used as donor and acceptor impurities, respectively. High carrier concentration (n, p≥101 8 cm− 3) and low resistivity films were obtained up to x=0.06 (E g =0.55 eV).