X-ray determination of strain in ion implanted GaN

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2002-05, Vol.190 (1), p.878-881
• Main Authors: Qadri, S.B., Molnar, B., Yousuf, M., Carosella, C.A.
• Format: Article
• Language: English
• Subjects: GaN; Ion implantation; X-ray diffraction
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/S0168-583X(01)01189-2

The out-of-plane c, and in-plane a, lattice parameters of wurtzite gallium nitride (GaN) films, grown on the [0 0 0 1] basal plane of sapphire have been determined and the impact of ion implantation having dose between 5×10 13 and 5×10 15 cm −2 investigated. The thickness of the GaN layers was in the 1–3.5 μm range. The overall effect of the (0 0 0 1) GaN growth on (0 0 0 1) sapphire is biaxial compression in wurtzite α-GaN. Earlier X-ray studies have indicated that the films of GaN grow either purely in α-GaN phase or in α-GaN phase with a cubic β-GaN component. In contrast, our high-resolution X-ray diffraction (XRD) measurement revealed two isostructural polymorphs of α-GaN phases having different lattice parameters. Influence of ion implantation is to increase the values of lattice parameters a and c and could be rationalized in terms of an increase in the defects. At doses above 5×10 15 cm −2, XRD analysis indicates the existence of an amorphous layer preventing the determination of a and c accurately.