The surfactant effects of antimony on the formation of InAsSb nanostructures on GaAs by metal-organic chemical vapor dep
- PDF / 515,144 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 7 Downloads / 145 Views
W2.6.1
The surfactant effects of antimony on the formation of InAsSb nanostructures on GaAs by metal-organic chemical vapor deposition J.G. Cederberg and R.M. Biefeld Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM, 87185-0601 ABSTRACT We have investigated InAsSb nanostructures formed on GaAs during MOCVD. The transition thickness from 2D growth to 3D growth is reduced by the addition of TMSb/Sb4. This is consistent with both an increase in the adatom diffusion length and a reduction in the epilayer/vapor surface energy attributed TMSb/Sb4. INTRODUCTION Compound semiconductor nanostructures have received a great deal of interest due to their potential to add an additional degree of freedom to the design of optoelectronic devices. There is also significant interest in investigating the fundamental physics of nanostructures that behave as quantum-confined systems. Self-assembly techniques utilizing the two-dimensional to three-dimensional growth transformation that occurs when a highly strained film is deposited on a substrate has been widely investigated to form nanostructures. One material system that undergoes this transformation is InAs on GaAs (100). Recent results have demonstrated 1.3 µm laser diodes with InGaAs quantum dot nanostructures.[1,2] However, extension to longer wavelengths might not be possible with this material system. In order to allow extension of emission from quantum dot nanostructures to longer wavelengths, we have investigated the addition of antimony to InAs to form InAsSb. Antimony is known to act as a surfactant in the epitaxial growth of both semiconductors and metals. It has been shown for Ge on Si(001) that the addition of Sb suppressed island formation that occurs without the addition of Sb.[3] Three-dimensional (3D) islands were suppressed in the case of Ag on Ag(111).[4,5] When Sb is added to InGaP grown on GaAs(100) it disrupts the phosphorus dimers present on the surface resulting in a reduction of the long range order present in this alloy at low growth temperatures.[6,7] When antimony is added during homoepitaxy on Ge (001) roughening of the surface occurs due 3D island growth attributed to alloying.[8] Similar effects are observed for the growth of Ag on Ge(100) where antimony promoted 3D island nucleation.[9] The specific effect Sb has on any given surface in unclear, but it does affect the transport of material on the surface and the bonds formed as adatoms are incorporated into the growing surface. This letter discusses observations on the effect the addition of Sb has on the nucleation of InAs nanostructures on GaAs. We observe that the addition of Sb causes a reduction in the critical thickness for the 2D to 3D growth transformation. This is explained using a kinetic model for island formation. We show that this reduction in the critical thickness is due to either an increase in the diffusion length of indium adatoms on the surface or the reduction in the vapor-film surface energy. EXPERIMENTAL DETAILS
W2.6.2
The growth of InAs nanostructure was performed
Data Loading...
