Thin (approx.0.2-0.5 μm), quaternary InxGa1-xAsySb1-y alloy films with compositions across the solid-phase miscibility gap were grown using ion-assisted deposition (IAD) on Si(001) and InP(001) substrates. The IAD chamber was designed to provide very-low-energy (<30 eV), high flux (approx.0.4 mA/cm2) Ar ion irradiation of the film surface during growth. Under conditions where ion irradiation effects were negligible, broadened x-ray diffraction peaks and increased surface roughness as a function of the proximity of the alloy composition to the center of the miscibility gap was observed. High-resolution cross-sectional transmission electron microscopy analysis of films, deposited nearly lattice matched on InP substrates, showed decomposition into columns elongated in the growth direction when the alloy composition was within the miscibility gap. A composition modulation wavelength of approx.7 nm was measured parallel to the film surface. The role of ion irradiation in suppressing decomposition in InGaAsSb alloy thin films deposited within the miscibility gap was investigated. Ar+ ion irradiation with a flux of approx.3 × 1015 cm2 s-1, and energy of 19-21 eV was found to improve both the homogeneity and electron mobility of the alloy films. This was attributed to the suppression of composition modulations by collisional mixing of the film surface during growth. Ar+ ion energies above 21 eV resulted in excessive structural damage to the films.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|State||Published - May 1 1995|
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering