This page has only limited features, please log in for full access.
Doping diamond layers for electronic applications has become straightforward during the last two decades. However, dislocation generation in diamond during the microwave plasma enhanced chemical vapor deposition growth process is still not fully understood. This is a truly relevant topic to avoid for an optimal performance of any device, but, usually, it is not considered when designing diamond structures for electronic devices. The incorporation of a dopant, here boron, into a lattice as close as that of diamond, can promote the appearance of dislocations in the epilayer. The present contribution analyzes the different processes that can take place in this epilayer and gives some rules to avoid the formation of dislocations, based on the comparison of the different dislocation generation mechanisms. Indeed, competitive mechanisms, such as doping atom proximity effect and lattice strain relaxation, are here quantified for heavily boron-doped diamond epilayers. The resulting growth condition windows for defect-free heavily doped diamond are here deduced, introducing the diamond parameters and its lattice expansion in several previously published critical thickness (hc) and critical doping level relationships for different doping levels and growth conditions. Experimental evidence supports the previously discussed thickness-doping-growth condition relationships. Layers with and without dislocations reveal that not only the thickness but also other key factors such as growth orientation and growth parameters are important, as dislocations are shown to be generated in epilayers with a thickness below the People and Bean critical thickness.
D. Araujo; F. Lloret; G. Alba; M. P. Alegre; M. P. Villar. Dislocation generation mechanisms in heavily boron-doped diamond epilayers. Applied Physics Letters 2021, 118, 052108 .
AMA StyleD. Araujo, F. Lloret, G. Alba, M. P. Alegre, M. P. Villar. Dislocation generation mechanisms in heavily boron-doped diamond epilayers. Applied Physics Letters. 2021; 118 (5):052108.
Chicago/Turabian StyleD. Araujo; F. Lloret; G. Alba; M. P. Alegre; M. P. Villar. 2021. "Dislocation generation mechanisms in heavily boron-doped diamond epilayers." Applied Physics Letters 118, no. 5: 052108.
Diamond surface properties show a strong dependence on its chemical termination. Hydrogen-terminated and oxygen-terminated diamonds are the most studied terminations with many applications in the electronic and bioelectronic device field. One of the main techniques for the characterization of diamond surface terminations is X-ray photoelectron spectroscopy (XPS). In this sense, the use of angle-resolved XPS (ARXPS) experiments allows obtaining depth-dependent information used here to evidence (100)-O-terminated diamond surface atomic configuration when fabricated by acid treatment. The results were used to compare the chemistry changes occurring during the oxidation process using a sublayer XPS intensity model. The formation of non-diamond carbon phases at the subsurface and higher oxygen contents were shown to result from the oxygenation treatment. A new (100) 1 × 1:O surface reconstruction model is proposed to explain the XPS quantification results of O-terminated diamond.
Gonzalo Alba; M. Pilar Villar; Rodrigo Alcántara; Javier Navas; Daniel Araujo. Surface States of (100) O-Terminated Diamond: Towards Other 1 × 1:O Reconstruction Models. Nanomaterials 2020, 10, 1193 .
AMA StyleGonzalo Alba, M. Pilar Villar, Rodrigo Alcántara, Javier Navas, Daniel Araujo. Surface States of (100) O-Terminated Diamond: Towards Other 1 × 1:O Reconstruction Models. Nanomaterials. 2020; 10 (6):1193.
Chicago/Turabian StyleGonzalo Alba; M. Pilar Villar; Rodrigo Alcántara; Javier Navas; Daniel Araujo. 2020. "Surface States of (100) O-Terminated Diamond: Towards Other 1 × 1:O Reconstruction Models." Nanomaterials 10, no. 6: 1193.
Concerning diamond-based electronic devices, the H-terminated diamond surface is one of the most used terminations as it can be obtained directly by using H2 plasma, which also is a key step for diamond growth by chemical vapour deposition (CVD). The resultant surfaces present a p-type surface conductive layer with interest in power electronic applications. However, the mechanism for this behavior is still under discussion. Upward band bending due to surface transfer doping is the most accepted model, but has not been experimentally probed as of yet. Recently, a downward band bending very near the surface due to shallow acceptors has been proposed to coexist with surface transfer doping, explaining most of the observed phenomena. In this work, a new approach to the measurement of band bending by angle-resolved X-ray photoelectron spectroscopy (ARXPS) is proposed. Based on this new interpretation, a downward band bending of 0.67 eV extended over 0.5 nm was evidenced on a (100) H-terminated diamond surface.
Gonzalo Alba; David Eon; M. Pilar Villar; Rodrigo Alcántara; Gauthier Chicot; Jesús Cañas; Juliette Letellier; Julien Pernot; Daniel Araujo. H-Terminated Diamond Surface Band Bending Characterization by Angle-Resolved XPS. Surfaces 2020, 3, 61 -71.
AMA StyleGonzalo Alba, David Eon, M. Pilar Villar, Rodrigo Alcántara, Gauthier Chicot, Jesús Cañas, Juliette Letellier, Julien Pernot, Daniel Araujo. H-Terminated Diamond Surface Band Bending Characterization by Angle-Resolved XPS. Surfaces. 2020; 3 (1):61-71.
Chicago/Turabian StyleGonzalo Alba; David Eon; M. Pilar Villar; Rodrigo Alcántara; Gauthier Chicot; Jesús Cañas; Juliette Letellier; Julien Pernot; Daniel Araujo. 2020. "H-Terminated Diamond Surface Band Bending Characterization by Angle-Resolved XPS." Surfaces 3, no. 1: 61-71.
Polymer-based composites are becoming widely used for structural applications, in particular in the aeronautic industry. The present investigation focuses on the mechanical integrity of an epoxy resin of which possible damage results in limitation or early stages of dramatic failure. Therefore, a coupled experimental and numerical investigation of failure in an epoxy resin thermoset is carried out that opens the route to an overall micromechanical analysis of thermoset-based composites. In the present case, failure is preceded by noticeable plasticity in the form of shear bands similar to observations in ductile glassy polymers. Thus, an elastic-visco-plastic constitutive law initially devoted to glassy polymer is adopted that captures the rate- dependent yield stress followed by softening and progressive hardening at continued deformation. A general rate-dependent cohesive model is used to describe the failure process. The parameters involved in the description are carefully identified and used in a finite element calculation to predict the material's toughness for different configurations. Furthermore, the present work allows investigation of nucleation and crack growth in such resins. In particular, a minimum toughness can be derived from the model which is difficult to evaluate experimentally and allows accounting for the notch effect on the onset of failure. This is thought to help in designing polymer-based composites.
Dery Torres; Shu Guo; Maria-Pilar Villar; Daniel Araujo; Rafael Estevez. Calibration of a Cohesive Model for Fracture in Low Cross-Linked Epoxy Resins. Polymers 2018, 10, 1321 .
AMA StyleDery Torres, Shu Guo, Maria-Pilar Villar, Daniel Araujo, Rafael Estevez. Calibration of a Cohesive Model for Fracture in Low Cross-Linked Epoxy Resins. Polymers. 2018; 10 (12):1321.
Chicago/Turabian StyleDery Torres; Shu Guo; Maria-Pilar Villar; Daniel Araujo; Rafael Estevez. 2018. "Calibration of a Cohesive Model for Fracture in Low Cross-Linked Epoxy Resins." Polymers 10, no. 12: 1321.
To obtain p-type doping of diamond through B ion implantation, thermal treatments are necessary to reconstruct the diamond lattice and to locate B atoms in substitutional lattice positions. The present contribution evaluates by STEM-EELS and CL spectroscopy the amorphisation of diamond lattice under the B+ bombardment and its subsequent reconstruction after the thermal treatment. In addition, TEM observations allowed localizing the boron spatial distribution. Carbon-related peaks of EELS spectroscopy shows a nearly complete recovery of the diamond lattice after thermal treatment. Indeed, at 1600 °C, sp2/sp3 ratio in implanted regions changes from 0.56 to 0.18 (0.15 value was measured before implantation). On the other hand, CL spectroscopy reveals how A-Band and free exciton emission peaks, which are quenched by B+ implantation, recover after annealing. Boron ion implantation was used to create ohmic contacts in two different diamond samples, treated with different annealing velocities. Crystalline reconstruction, evidenced by TEM data explains the related electric behaviour. Nanoscale evidences of amorphisation, lattice reconstruction and dopant activation are presented and discussed in this work.
José C. Piñero; María P. Villar; Daniel Araujo; Josep Montserrat; Bernat Antúnez; Philippe Godignon. Impact of Thermal Treatments in Crystalline Reconstruction and Electrical Properties of Diamond Ohmic Contacts Created by Boron Ion Implantation. physica status solidi (a) 2017, 214, 1 .
AMA StyleJosé C. Piñero, María P. Villar, Daniel Araujo, Josep Montserrat, Bernat Antúnez, Philippe Godignon. Impact of Thermal Treatments in Crystalline Reconstruction and Electrical Properties of Diamond Ohmic Contacts Created by Boron Ion Implantation. physica status solidi (a). 2017; 214 (11):1.
Chicago/Turabian StyleJosé C. Piñero; María P. Villar; Daniel Araujo; Josep Montserrat; Bernat Antúnez; Philippe Godignon. 2017. "Impact of Thermal Treatments in Crystalline Reconstruction and Electrical Properties of Diamond Ohmic Contacts Created by Boron Ion Implantation." physica status solidi (a) 214, no. 11: 1.
A transmission electron microscopy (TEM) study of superconducting nanocrystalline diamond (NCD) continuous layers is reported. The high resolution transmission electron microscopy (HREM) and the diffraction contrast modes of observations are used to reveal the nanograins configuration. Three types of them are observed: first, close to the interface with the Si/SiO2 substrate, 10–20 nm‐sized diamond seeds resulting from the 5 nm size diamond powder deposition before growth that show some regrowth during CVD process, second a diamond overgrown layer, quasi‐epitaxially by coalesced larger NCD grains, and finally, up to the free surface, a thin disordered region composed of nanocrystallites smaller than 6 nm. This last layer was not nominally expected and is attributed to a renucleated‐like (RND) carbon layer embedding ultra NCD grains. Diffraction contrast observations confirm this HREM observed behavior.
M. P. Villar; Ma. P. Alegre; D. Araujo; E. Bustarret; P. Achatz; L. Saminadayar; Christopher Bauerle; O. A. Williams. A microstructural study of superconductive nanocrystalline diamond. physica status solidi (a) 2009, 206, 1986 -1990.
AMA StyleM. P. Villar, Ma. P. Alegre, D. Araujo, E. Bustarret, P. Achatz, L. Saminadayar, Christopher Bauerle, O. A. Williams. A microstructural study of superconductive nanocrystalline diamond. physica status solidi (a). 2009; 206 (9):1986-1990.
Chicago/Turabian StyleM. P. Villar; Ma. P. Alegre; D. Araujo; E. Bustarret; P. Achatz; L. Saminadayar; Christopher Bauerle; O. A. Williams. 2009. "A microstructural study of superconductive nanocrystalline diamond." physica status solidi (a) 206, no. 9: 1986-1990.