Alexis Bavard

Delta-Doping of Epitaxial GaN Layers on Large Diameter Si(111) Substrates

We report on silicon n-type delta (δ)-doping of gallium nitride (GaN) epitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) on silicon (111) substrates. In a series of group III–nitride epitaxial structures a ~1-µm-thick Si bulk-doped GaN layer is replaced by 100, 50, 10, 5, or 1 Si δ-doped planes. While Si bulk-doping of GaN aggrandizes the in-plane tensile stress and the wafer bow with respect to undoped structures, δ-doping is found to reduce both stress and wafer bow. Two-dimensional carrier sheet densities between 1012 and 1013 cm-2 per δ-doped plane and electron mobilities of 1429 cm2 V-1 s-1 are achieved.

Direct wafer bonding for nanostructure preparations

Direct Wafer Bonding has been widely developed and is very attractive for a lot of applications. Using original techniques based on direct bonding enable to carry out specific engineered substrates. Various illustrations are given among which twisted Si-Si bonded substrates, where buried dislocation networks play a key role in the subsequent elaboration of nanostructures.

Metal positioning on silicon surfaces using the etching of buried dislocation arrays

Large-area Si(001) nanopatterned surfaces obtained by etching dislocation line arrays have been used to drive the positioning of metallic islands. A method combining wafer bonding of (001) silicon on insulator layers and preferential chemical etching allows controlling the periodicity of square trench arrays in the 20-50 nm lateral periodicity range with an accuracy of less than 1 nm and a depth of about 4-5 nm. The interfacial area containing the dislocation line plane can be removed and a single crystal maintaining the morphological patterning can be obtained. It is shown that oxidized or deoxidized silicon nanopatterned surfaces can drive the positioning of Ni, Au and Ag islands for a 20 nm lateral periodicity and that a lateral long range order, directly transferred from the dislocation network, can be obtained in the Ni and Au cases.

From silicon direct wafer bonding to surface nano-patterning: a way to innovative substrate elaboration

Self-assembled configurations of nanostructures are expected to play an increasingly important role in devices design, as an alternative to conventional microelectronics technology. Conventional techniques are generally limited by the lack of simultaneous control on positioning, density and size uniformity of the nanostructures. To overcome these problems a new substrate based on controlled direct twist wafer bonding and preferential chemical etching has been developed.