PbTe films grown by hot wall epitaxy on sapphire substrates

A 'hot wall epitaxy' is applied to grow PbTe thin films on sapphire substrates with BaF₂ buffer layer deposited by molecular beam epitaxy (MBE). The microstructural and strain state characteristics of PbTe layer were examined with high resolution X-ray diffraction techniques. The epilayer is composed of two (1 1 1)PbTe||(0001)Al₂O₃ epitaxially oriented domain variants. The domains are azimuthally rotated and their interfacial directions relative to the substrate are [011̄] PbTe||[21̄1̄0]Al₂O₃ and [1̄54̄] PbTe||[2 1̄ 1̄ 0]Al₂O₃, respectively. Another possible alignment of the domain variant corresponds to [31̄2̄] PbTe[31̄2̄0]Al₂O₃ orientation. The strain state analysis of PbTe layer points to its relaxation via domain formation and high dislocation density generation in the lattice. Despite the domains formation the measured mobility of electron carriers is approximately 1600 cm²/V s and 30000 cm²/V s at 300 K and 77 K, respectively. The theoretical analysis of the measured electrical properties indicates that the scattering by acoustic and optical phonons is the factor affecting the conduction process.