InP islands on InGaP/GaAs(001): island separation distributions

• Published in: Surface science 1997-12, Vol.393 (1), p.24-33
• Main Authors: Varma, S., Reaves, C.M., Bressler-Hill, V., DenBaars, S.P., Weinberg, W.H.
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Epitaxy; Exact sciences and technology; Indium phosphide; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Models of surface kinetics; Physics; Single crystal surfaces; Structure and morphology; thickness; Surface morphology; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(97)00231-8

Heteroepitaxy of InP on InGaP/GaAs(001) has been studied using atomic force microscopy (AFM) as a function of substrate temperature and misorientation. Stranski-Krastanov growth of InP on GaAs results in three types and sizes of islands. The smallest and medium-sized islands are coherently strained to the substrate, whereas dislocations are seen in the largest islands. Growth, morphology and island separation distributions have been studied for the small and medium islands. Scaling in the radial distribution function indicates a uniformly random growth of medium-sized InP dots on all the substrates. However, on substrates grown at 650°C and misoriented by 2°, clustering of islands is also observed. We suggest that is due to the preferential growth of mediumsized islands at the step edges of the substrate. Separation distributions along and perpendicular to the step edges of this surface reveal that the step edges are decorated by clusters of 6–8 islands having an average period of 2 μm between them. These clusters exhibit long-range ordering and have a potential for device applications. Radial separation distribution studies indicate that the substrate morphology and topography are crucial for achieving a desirable distribution of islands. Moreover, the small InP islands and the dislocated islands are uniformly distributed on all the substrates irrespective of the growth temperature or misorientation, suggesting a different nucleation mechanism than for the medium-sized InP islands.