The growth of epitaxial aluminium on As containing compound semiconductors

The growth of epitaxial aluminium on different (1 0 0) oriented compound se miconductors grown using the molecular beam epitaxy technique have been stu died. After deposition of the first complete adlayer between the aluminium and the GaAs surface as evidenced by in situ reflection high electron energ y diffraction (RHEED), ex situ atomic force microscopy (AFM) images agree t hat subsequent aluminium deposition is via a 3D nucleated growth mode. RHEE D observations during continued deposition of epitaxial aluminium indicate a 2D growth mode dominated by the (1 0 0) orientation. AFM images of the su rface of the aluminium reveal that the surface morphology consists of a pla teau-valley structure, while transmission electron microscopy characterisat ion reveals that the aluminium is all (1 0 0) oriented single crystal. For growth of epitaxial aluminium on different (1 0 0) compound semiconductors the resultant hillock-valley morphology of the aluminium is remarkably simi lar regardless of the underlying semiconductor. There is no apparent differ ence between the aluminium growth on GaAs and Al0.6Ga0.4As indicating that the aluminium content of the semiconductor is having no effect on the growt h of the aluminium, whereas there can be a difference in the hillock widths for aluminium grown on In0.53Al0.47As and In0.55Ga0.45As. The dominant ori entation that the aluminium recrystallises to, appears to be determined by the strain between the aluminium 3D nucleates and the underlying semiconduc tor with (1 O O) oriented aluminium for tensile strain (growth on GaAs and AlGaAs) and (110) oriented aluminium for compressive strain (growth on InAl As and InGaAs). (C) 1999 Elsevier Science B.V. All rights reserved.