On Energy and Dose Effects During Ion-Assisted Epitaxial Growth of InAs on Si(100)

Abstract

ABSTRACTEpitaxial InAs films have been grown on Si(100) substrates using triode ion-assisted deposition (TRIAD). The ratio r of the impinging Ar ion flux J to the deposited InAs flux was varied from 2.5 to 8.5 for Ar ion energies E from 5 to 55 eV. The growth temperature T was 350°C while the growth rate R was fixed at 0.6 μm/h. Two types of experiments were carried out. First, in order to investigate ion damage effects, X-ray diffraction rocking curve full-widths at half-maximum (FWHM) were measured as a function of E and r. In these experiments, the first 50 nm of InAs was always grown under the same conditions, r = 5 and E = 25 eV, in order to eliminate possible complicating effects caused by ion irradiation during InAs nucleation on Si, followed by 550 nm of growth at different E and r values. FWHM values increased with increasing E and r from 2800 arcsec, a value limited by defects arising from the 11% mismatch between InAs and Si, to 8900 arcsec as a result of ion damage. The FWHM value was found to be dependent on the total number of atomic displacements due to ion irradiation, estimated using a modified Kinchin-Pease expression. In the second set of experiments, E during the first 50 nm of growth was varied while ion irradiation damage in the remaining 5500 nm was minimized. Increasing E from 15 to 40 eV resulted in a decrease in the FWHM from 5500 to 2600 arcsec, followed by a gradual increase when E was increased above 40 eV. Ion irradiation at the onset of film growth thus reduced the propagation of defects from the InAs/Si interface into the film.