Observation of hardening during relaxation of InGaAs on GaAs

• Published in: Journal of physics. D, Applied physics Vol. 36; no. 10A; pp. A198 - A201
• Main Authors: Tanner, B K, Parbrook, P J, Lunn, B, Hogg, J H C, Keir, A M, Johnson, A D
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bristol IOP Publishing 21.05.2003; Institute of Physics
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities: doping, implantation, distribution, concentration, etc; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Physics; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Gallium arsenides; Inorganic compounds; Misfit dislocations; Dislocation nucleation; Semiconductor materials; Ternary compounds; Doping; Elasticity; XRD; Experimental study; Silicon additions; High-resolution methods; Indium arsenides; Thickness; Impurities; Molecular beam epitaxy; Strain hardening
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/36/10A/340

The relaxation of Si-doped In0.04Ga0.96As epitaxial layers on (001) GaAs has been studied by in situ high-resolution x-ray diffraction during molecular beam epitaxy growth. By use of a novel technique to measure the wafer curvature with very high sensitivity, we have identified three regions in the relaxation process as a function of epilayer thickness. For thickness below that for multiplication of the slow A(g) misfit dislocations, the behaviour is effectively elastic, there being no detectable change in curvature at the critical thickness for dislocation nucleation. Beyond the thickness at which the A(g) dislocations multiply there is total or substantial relaxation, with very little increase in elastic strain as a function of thickness in this region corresponding to stage 1 of work-hardening in cubic materials. At much greater thickness, corresponding to stage 2 of bulk work-hardening, only partial relaxation occurs as the lattice hardens to the creation of misfit dislocations. Substantial elastic strain is observed to be locked into highly mismatched epilayers many times thicker than the critical thickness.