Team Leader: Fabrice GOURBILLEAU

The NIMPH team is made up of about 20 persons (5-8 PhD students, post-doctoral or guest researchers). This team is involved in the study of Integrated Nanostructures for Microelectronics and PHotonics. Our objectives are to develop structures in the form of thin films with innovative features in the fields of microelectronic and photonics

Microelectronic

The NIMPH group develops and examines materials containing nanostructures for potential applications in photovoltaic (PV) cells and electronic memories

Photovoltaic solar cells-based nanoparticle

This study aims to demonstrate the feasibility of photovoltaic cells based on nanoparticles or silicon nanowires whose bandgap is adjusted by quantum confinement of carriers in nano-objects. The potential efficiency of the combination of that kind of cell to produce a multijunction solar cell is estimated at 42% (more - project DUOSIL)

Nanomemory

The use of nanocrystals (NCs) embedded in SiO₂ as charge storage elements has been widely explored in recent years. The replacement of the floating gate of polySi memory by a 2D network of NCs has many advantages, but the compromise between programming speed and retention time was not found. This can be achieved using the grid of insulating materials with high dielectric constant (high k) as HfSi_xO_yN_z. (More - project NOMAD)

Photonic

The NIMPH team develops thin films for photonics, semiconductor or conductive, doped with rare earth (and/without) nanostructured sensitisers

IR emitters based on nanostructured thin film

The indirect excitation of rare earth ions (Er³⁺,Nd³⁺ ...) by nanoamas (agglomerates and nanocluster) of Si (nc-Si) in silicon based materials offers exceptional potential as an active medium for compact and low cost photonic devices, such as optical amplifiers, light emitting diodes (LEDs), or lasers. The manufacturing process (Si-rich silicon oxide: SRSO) can be achieved according to the method specific to the silicon technology with the possibility of either optical or electrical excitation

• The material is doped with erbium Si:Er³⁺for IR emitters at 1.55 µm (more- Lancer European Project)
• The material is doped with Neodymium Si:Nd³⁺ for IR emitters at 1.06 µm (more - National Daphnes project and Integrated Action Polonium)

The ZnSe:Cr²⁺ thin films: Within infrared laser based on II-VI semiconductor doped with transition metals, systems based on massive crystal of ZnSe:Cr²⁺ are probably those with the greatest performance. The emission range from 2.3 to 3.4 µm, is suitable for applications in the field of environment, biology, medicine. The originality of this study is to take advantage of both the effects of quantum confinement related to the size of nanograins of ZnSe and the possibility of electrical excitation

IR emitters in thin film

The transparent conductive oxides Ga₂O₃ thin films: The main objective of this topic is the growth and the characterization of thin films of transparent conductive oxides (TCOs) doped with rare earth (Nd, Er, ...). The goal is to get the best compromise between electrical conductivity and optical transparency to achieve a competitive electroluminescent device.

Modelling of the electromagnetic field in the planar waveguide.

The aim is to demonstrate the feasibility and interest of planar waveguide amplifiers based on Si-rich silicon oxide: SRSO doped by rare earth. We develop the calculations in different 3D structure corresponding to different possible geometries (layer active 'or not buried', dimensions of the straight section of the guide, optical indices). We apply the ADE-FDTD (Auxiliary Differential Equation Finite Difference Time Domain) method to solve coupled differential equations describing the propagation of the electromagnetic field (E, H) and different populations (fundamental or excited states) of silicon nanograins and rare-earth ions.

Modeling of atomic and electronic structures of Si-SiO₂

Based on 'ab initio' density functional theory (DFT), we study the atomic and electronic structures involved in photoluminescence properties of silicon nanograins and rare-earth ions embedded in an insulating SiO₂ matrix. We demonstrate the effects of grain size, the average grain and rare earth position (interstitial or substitutional) of these ions in the insulating matrix, the crystalline nature of the insulating matrix (quartz, cristoballite, tridymite). We calculate the properties of absorption and propose mechanisms for interaction between silicon nanograins and rare-earth ions.

Plasmonic

Starting in Autumn 2009 within the framework of Shaman ANR white project (Project of French National Research Agency), we will develop the plasmonic theme. This theme will be developed through the study of composite glasses made up of individual or arrays (periodic) of metallic nanostructures included in SiO2 type dielectric. These composite glasses will be studied experimentally by optical and structural characterization. The electro-dynamic behaviour associated with singular metallic or arrayed nanostructures will be studied theoretically by FDTD simulation. (more- ShaMaN project)