h-BN has emerged as an important multifunctional material system[i],[ii],[iii] with wide direct bandgap, high resistance to oxidation, and chemical inertness, which may find applications in both optoelectronics and microelectronics. h-BN is also an interesting material because it has the same crystalline structure as wurtzite GaN used for optoelectronic applications, but with greater hardness and thermal conductivity. Moreover, it can be doped (p- and n-types) to form p-n junctions. In spite of its strong potential, BN is the least investigated among the III-Nitrides semiconductors because the growth of high crystalline quality has proved to be challenging[iv]. Several research programs on BN materials have been recently funded by research agency at the international level (Darpa, DoD, NSF). This project will offer a powerful experimental platform in the fields of MOVPE growth and next generation optoelectronic device development to investigate fundamental properties and explore applications of hexagonal boron nitride (h-BN) material. The ability to understand and design new semiconductor devices, such as neutron detector and XUV photodiode, will be a significant scientific achievement. Furthermore, since h-BN shares the honeycomb lattice structure with graphene and has a lattice constant that is only 1.7% larger, while exhibiting high intrinsic resistivity due to its wide bandgap, it is thus an excellent and unique substrate capable of preserving graphene’s intrinsic properties[v].
To accelerate French research in this area, this project focuses on the growth of wafer scale (up to 2-inch in diameter) of planar and nanostructured (e.g., 2D atomic layers, nanorods, and nanostripes) h-BN using 4″ state-of-the-art metal organic vapor phase epitaxy (MOVPE) system. As a proof of concept, innovative demonstrators such as h-BN-based soft-X ray / extreme UV photodetectors and neutron sensors will be fabricated. We will thoroughly investigate the growth, fundamental properties, and processing of these materials on different substrates, including the vastly less expensive silicon. Beyond the achievement of operating devices with improved performance, we aim to improve the material quality, with particular emphasis on improving the basic material properties of h-BN epilayers, including the crystalline quality, carrier mobility-lifetime (μτ) product and electrical resistivity (ρ).
The project will be developed in the frame of a collaboration with four research laboratories and one technology transfer platform (Institut Lafayette) covering a wide range of skills and knowledge including BN epitaxy grown by MOVPE, device processing dedicated to detectors, and graphene epitaxy. The academic partners are leaders in their field, including GeorgiaTech (Walt de Heer group, Atlanta, US), IEMN (Lille), Institute of Optoelectronics (Ulm, Germany), and LPN (Marcoussis, France). Boron alloyed III-nitrides have already led to the demonstration of higher-performance UV sources, transistors and photodetectors by our group. More recently, h-BN and 2D h-BN layers have been obtained[vi],[vii] on both 2” sapphire and silicon substrate using MOVPE.
Doctoral School: EMMA
How to apply
In order to prepare a PhD thesis within the Lorraine Université d’Excellence Program, the interested candidate should consult the PhD topics offered in each social and economic challenges.
These PhD thesis topics are proposed by faculty members or researchers accredited to supervise research.
Candidate application period: according to graduate school schedule
- visit graduate school web site for application rules. EMMA, doctoral school
- contact mail adresses :
doctoral school director Denis.maillet (@) univ-lorraine.fr
secretary chrsitne.sartory (@) univ-lorraine.fr
Each candidate may submit an application on up to three separate research topics.
Application analysis period by each graduate school
The graduate school reviews the applicants for a doctoral contract in the relevant disciplines. They check the level of supervision for each supervisor and the situation of trained doctors. Each candidate will meet the laboratory director, supervisor or a representative from the graduate school. This interview is to identify the candidate’s motivations and suitability as a candidate for the PhD project proposed by the supervisor. A recommendation will be made to the graduate school. This will summarize the strengths and/or weaknesses of the application.
PhD grants will include monthly income for the PhD student (roughly 1700 € for research only, complement can be provided for teaching missions) and environment for research in the research unit.
Please be aware that in order to offer a variety of subjects, more positions are posted here than available funding. The LUE executive committee will make the final choice on the granted funding (up to 12 positions), based on the recommendations by the doctoral schools.
[i] C. G. Lee et al., Frictional characteristics of atomically thin sheets, Science 328, 76–80 (2010)
[ii] Y. C. Zhu, et al., Ultrathin BN nanosheets protruding from Si3N4 nanowires, Nano Lett. 6, 2982–2986 (2006)
[iii] C.H. Jin et al., Fabrication of a freestanding boron nitride single layer, Phys. Rev. Lett. 102, 195505 (2009)
[iv] R. Dahal et al., Epitaxially grown semiconducting h-BN as a deep ultraviolet photonic material, Appl. Phys. Lett. 98, 211110 (2011)
[v] W. Yang et al., Epitaxial growth of single-domain graphene on hexagonal BN, Nat. Mat. 12(9), 792–797 (2013)
[vi] X. Li et al., Large-area two-dimensional layered h-BN grown on sapphire by MOVPE, Crystal Growth & Design (2016), in press
[vii] T. Ayari et al., Wafer-scale controlled exfoliation of MOVPE grown InGaN/GaN MQWs structure using low-tack 2D layered h-BN, Appl. Phys. Lett. (2016), in press