GaAsrGaAs twist-bonding for compliant substrates: interface structure and epitaxial growth

We investigated by transmission electron microscopy TEM.the structure of the interface fabricated by twist-bonding two GaAs wafers in order to obtain a compliant substrate. The interface contains a dense network of pure screw dislocations even for twist angles as large as 168. Then, one side of the assembly was thinned down to a few nanometers with mismatched In xGa1yx As layers grown on it. The structural quality of these layers has been studied by X-ray diffraction XRD.and by TEM. The structural quality generally appears weakly improved for the growths realised on our compliant substrates. One of the problems encountered is that the thinnest compliant layers appear to be unstable during the heating stage required by the epitaxy process. q2000 Elsevier Science B.V. All rights reserved.