The zincblende structure of GaAs gives rise to two types of steps on a GaAs(100) surface. In a model using abrupt bulk-termination, these steps would be labelled A or B, depending upon whether they are As or Ga terminated, and in the [011] or [011] directions, respectively. Since these steps are structurally and chemically different, one expects them to have different roles in epitaxy. We have used reflection high-energy electron diffraction (RHEED) to study the morphology of each of these two types of steps on surfaces prepared by molecular beam epitaxy (MBE). The results show large differences in the qualitative and quantitative structural disorder of these two step configurations. During static conditions of no growth, but with an As4 flux provided, the A-steps were straight over long distances. However the terraces between them exhibit large fluctuations in length. Conversely, the B-steps are highly kinked, but are seperated by terraces which show little length variation. For the A-steps, the terrace length fluctuations are greatly reduced by changing the reconstruction from the 2×4 or 1×1 or by initiating growth. During growth, the difference between RHEED intensity oscillations on the two surfaces is striking. For identically prepared and simultaneously mounted wafers that had been oriented 2° from the (100), the A-surface showed intensity oscillations over a range in temperatures. By contrast, the B-surface exhibited only faint oscillations that were rapidly damped. In addition, during growth of GaAs on stepped Si(100) surfaces, growth on surfaces prepared to yield A-steps gave much smoother morphologies than on surfaces prepared to yield B-steps.

It is now clear that both the atomic and magnetic properties of epitaxial Fe films can be controlled by the precise nature of the substrate which acts as the template for the growth. We have investigated the role of defects and strain arising from lattice mismatch on the growth and the magnetic properties of the Fe films. The films were grown by molecular-beam epitaxy (MBE) on three different well characterized surfaces: GaAs(100), In0.2Ga0.8As(100), and Fe(100). The first two surfaces were also prepared by MBE. This mole fraction of In was chosen to match the lattice constant of bulk α-Fe. The growth of the Fe film was characterized by using reflection high-energy electron diffraction (RHEED) and the results indicate that the morphology of the Fe films is smoother on the InGaAs surface than on the GaAs surface. Yet is is still much rougher than the growth on Fe(100) substrate. The magnetic properties were measured by using a SQUID magnetometer and coercivity values are comparable to that of the films grown on ZnSe.1

The magnetic properties of epitaxial iron films have been studied. The iron films were grown on {100} GaAs and GaInAs substrates. Both the magnitude of the anisotropy energies and direction of the easy axes were studied using a SQUID magnetometer. In particular, measurements were made of the magnetization in the plane of the film along the 〈100〉 and 〈110〉 directions. From these measurements the magnitude of the anisotropy energy and the direction of the easy axis were determined. Also measurements of the coercivity of the films were made using a magneto-optic Kerr effect system. These results are compared with those determined previously for iron films grown on GaAs.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation D. Saluja, P. R. Pukite, S. Batra, P. I. Cohen; Summary Abstract: Reflection high energy electron diffraction measurements of AlGaAs growth instabilities and roughening rates on misoriented substrates. Journal of Vacuum Science & Technology B: Microelectronics Processing and Phenomena 1 May 1987; 5 (3): 710–711. https://doi.org/10.1116/1.583813 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAVS: Science & Technology of Materials Interfaces and ProcessingJournal of Vacuum Science & Technology B Search Advanced Search |Citation Search

We have used reflection high energy electron diffraction (RHEED) to follow the growth of GaAs on misoriented GaAs(100), using molecular beam epitaxy (MBE). We find anisotropies in the step order, kink density and the growth oscillations as a function of substrate misorientation and direction of surface misorientation. For comparison in a simple system, growth of Ge on Ge(100) is also followed. On the singular Ge(100) surface, we observe strong RHEED oscillations accompanied by a strong anisotropy in the nucleation of the islands during growth. These islands show up as long intersecting streaks in the diffraction pattern when the electron beam is incident along the [010] direction. In the presence of As4, these anisotropic features become more striking and stronger RHEED oscillations are observed over a wider temperature range.