Microsc. Microanal. Microstruct. 6, 491-498 (1995)
DOI: 10.1051/mmm:1995140

Investigation of Strain Relaxation Mechanisms in InGaAs/GaAs Single Layer Films

Filippo Romanato¹, Antonio Vittorio Drigo¹, Laura Francesio², Paolo Franzosi², Laura Lazzarini², Giancarlo Salviati², Massimo Mazzer³, Maria Rita Bruni⁴ et Maria Grazia Simeone<sup>4

1</sup>  Dipartimento di Fisica and Istituto Nazionale di Fisica della Materia (INFM), Università di Padova, Via Marzolo 8, 35131 Padova, Italy
²  Istituto CNR-MASPEC, via Chiavari 18/A, 43100 Parma, Italy
³  Department of Materials, Imperial College, Prince Consort Road, London 3W72BP, U.K.
⁴  C.N.R. I.C.M.A.T, Via Salaria km 29, 00015 Roma, Italy

Abstract
In this work a strict comparison of the results obtained on InGaAs/GaAs heterostructures by HRXRD and RBS-channeling analysis shows a discrepancy in the In atomic fraction determined by the two techniques. The discrepancy leads to a difference in the reference lattice parameter of the relaxed film and, therefore, changes the description of the strain relaxation rate. After a discussion on the possible reasons for this discrepancy, the results have been interpreted as the influence of the atomic degrees of freedom internal to the lattice unit cell which could determinate the equilibrium shape of the unit cell. While it has been not strictly proved, the most reasonable hypothesis to explain the experimental results is that local ordering leads to a relaxed unit cell which is slightly tetragonal.

PACS
6865 - Low dimensional structures: growth, structure and nonelectronic properties.
6220F - Deformation and plasticity.
8140L - Deformation, plasticity and creep.
6825 - Mechanical and acoustical properties of solid surfaces and interfaces.
7920N - Atom , molecule , and ion surface impact and interactions.
6180M - Channelling, blocking and energy loss of particles.
6160 - Crystal structure of specific inorganic compounds.
6110F - Experimental X ray diffraction and scattering techniques.

Key words
channelling -- deformation -- gallium arsenide -- III V semiconductors -- indium compounds -- lattice constants -- Rutherford backscattering -- semiconductor heterojunctions -- X ray diffraction -- strain relaxation -- single layer films -- heterostructures -- RBS channeling -- In atomic fraction -- lattice parameter -- atomic degrees of freedom -- local ordering -- relaxed unit cell -- high resolution X ray diffraction -- semiconductors -- InGaAs GaAs


© EDP Sciences 1995