EFFECT OF GRAVITY ON COPPER PHTHALOCYANINE THIN-FILMS .3. MICROSTRUCTURE COMPARISONS OF COPPER PHTHALOCYANINE THIN-FILMS GROWN IN MICROGRAVITY AND UNIT GRAVITY

This is the third paper in a series of three describing the first closed-cell physical vapor transport (PVT) experiments in which thin films of organic pigments were epitaxially deposited onto highly oriented seed films of another organic. Furthermore, the experiments were conducted in both low earth orbit (LEO) on the Space Shuttle Orbiter and in the laboratory as ground controls using the 3M-PVTOS (PVT of organic solids) apparatus. In this last paper of the series, scanning electron microscopy is used to compare the ground control CuPc samples with the LEO-grown samples. The results are notable because they show that a distinctly different microstructure exists in the centers of the LEO-grown films from that in the ground control films. A further very important observation is that the circular perimeters of the LEO-grown films have a microstructure much like that of the ground control films in both their center and edge regions. This provides a strong self-consistency check that the structural differences are attributable to the absence or presence of convection and not some other PVT parameter or ampoule artifact. The form and radial variation of the physical microstructure among the LEO and ground control samples are fully consistent with the observations and conclusions of the optical, visible spectroscopy, ellipsometry, interferometry, reflection X-ray diffraction and IR spectroscopy of the two preceding articles in this series. © 1990.