An x-ray Fourier line shape analysis of hexagonal tellurium films II: Vacuum evaporated at low temperature (133 K)

Abstract

Detailed X-ray line profile studies were carried out on thin hexagonal tellurium films of thickness 90–1000 nm. The films were deposited by vacuum evaporation at a low substrate temperature (133 K) under both normal (thickness range, 90–900 nm) and oblique (thickness range, 495–1000 nm) incidences with varying deposition rates. Films formed at high deposition rates under both normal and oblique incidence as well as at a low deposition rate under oblique incidence showed a considerable size effect D av (134Å, 150Å and 123Å respectively), appreciable microstrain (〈ε L 2〉 − 〈ε〉 2) 1 2 ) ((4.1−1.7) × 10 −3, (3.3−1.7) × 10 −3 and (3.0−2.3) × 10 −3 respectively) and a near isotropy in the size and strain parameters. The domain sizes D e from the fault-affected reflections ( H  K = 3 N ± 1, L 0 odd or even) indicated that the intrinsic stacking fault probability α and the growth stacking fault probability β are negligible. The dislocation density ϱ was found to be appreciable (about 10 11 cm −2) in all cases. Tellurium films grown on glass substrates indicated, as before, the presence of a c axis texture. Line shift analysis showed that the average residual internal stresses σ as well as the lattice parameter changes Δ a and Δ c were small. However, neither the angle of incidence of the vapour beam nor the rate of deposition had a marked effect on the microstructures of these films deposited at low temperature.