AVS 49th International Symposium
    Plasma Science Thursday Sessions
       Session PS+TF-ThM

Paper PS+TF-ThM2
Low-Temperature Plasma Migration Enhanced Epitaxy of CuInSe@sub 2@ on GaAs

Thursday, November 7, 2002, 8:40 am, Room C-103

Session: Plasma Enhanced Deposition
Presenter: B.J. Stanbery, University of Florida
Authors: B.J. Stanbery, University of Florida
S. Kincal, University of Florida
S. Kim, University of Florida
T.J. Anderson, University of Florida
O.D. Crisalle, University of Florida
Correspondent: Click to Email
A comparison of migration-enhanced epitaxial growth@footnote 1@ of CuInSe@sub 2@ on GaAs at 350°C with either a thermal cracker or ECR helicon plasma selenium source demonstrates both improved crystallinity and enhanced selenium incorporation using the plasma cracker. Mass spectrometric characterization of the flux from the effusion source coupled to a magnetic-mirror confined 2.45GHz plasma cracker shows 50% enhancement of the Se monomer to dimer flux ratio compared to the thermal double-oven with its cracking zone operating at 1200K, and no measurable ion flux outside the plasma source. Samples grown using the ECR plasma cracker were characterized by a number of differences from all other growth experiments that used the thermal source. The improvement of CuInSe@sub 2@ epilayer crystallinity is confirmed by the XRD data irrespective of the atomic [Cu]/[In] ratio of the resultant films, which exhibit an order of magnitude reduction in incoherent scattering compared to samples grown with the thermal source, particularly at low angles. Films grown with the plasma source that contain excess copper yield compositions that lie well into the selenium-rich domain of the equilibrium ternary phase field, with little indication of diffraction corresponding to the Cu@sub 2@Se binary compound which coexists in equilibrium with CuInSe@sub 2@ when the overall composition is copper-rich. In contrast, such a peak is always seen in significantly copper-rich layers grown with the thermal source. The higher level of selenium incorporation resulting from MEE growth with the plasma source is discussed in the context of a recent theoretical lattice defect model for CuInSe@sub 2@ that predicts a significant reduction in the electrical compensation ratio of indium-rich CuInSe@sub 2@ incorporating a stoichiometric excess of selenium.@footnote 2@ @FootnoteText@ @footnote 1@ Y. Horikoshi, et al., Jap. J. Appl. Phys. 25, L868 (1986).@footnote 2@ B.J. Stanbery, Ph.D. Dissertation, U. Fl.(2001).