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B4.2 Programme of Jointly Executed Research Activities

Joint research activities carried out by DiNAMITe will build on the funded research existing at partner groups and mainly directed towards addressing difficult challenges in cooperation that are likely to spin out new funding opportunities. The issues to be addressed are organized into 4 sub work packages (WP1(a)- 4(a)) each managed by the parent work package (WP1-4)

WP1(a): Jointly executed research in growth of materials and devices
This sub work package will address the challenges in the growth of complex novel semiconductor materials and devices based on dilute nitride compounds

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  Doping studies with different dopants:(Be, C, Si, Te) to study electrical properties and interaction of dopants with N. This important field has received very little attention so far and clearly calls for action, otherwise electronic devices based on dilute nitrides will not be achievable.
  
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  Atomic-layer-type growth modes such as MEE, ALE, which might be more suited to the typically used low-temperature growth of dilute nitrides than continuous growth
  
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  Different routes to reach long wavelengths (QWs, QDots, different alloys) hence to push the long-wavelength limit of GaAs-based materials as far as possible
  
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  Growth of complex structures with well-defined strain in the layers, with and without strain compensation by the GaAsN
  
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  InGaAsSbN/GaAs with strain-mediating layers
  
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  In(Ga)As(N) QWs with InAs- (or more generally InGaAsN-) Quantum Dots embedded in them
  

WP2(a) : Jointly executed research in characterization and physical properties
This sub work package will address the physical properties, band structure, structural, optical and electronic characterization issues

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  Structural characterisation of novel materials: These will be characterised by AFM, STM and TEM. In parallel X-ray analysis will be performed in order to determine the strain fields in the structures. The accurate determination of the N content in the structures is known to be a very difficult task. The combination of various complementary characterisation techniques (microscopy, X-ray (diffraction & photoelectron spectroscopy), Raman spectroscopy and SIMS) should yield an accurate measurement of the N content (average value, dispersion) and hence an understanding of the incorporation process.
  
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  Defect characterisation and material improvement: This joint activity aims to carry out a detailed investigation of the defects related to the Nitrogen incorporation in the material. These characterisations are essential since the incorporation of nitrogen in III-V compounds is usually accompanied by a drastic degradation of the optical and electrical properties of the structures. These will be studied by high resolution X-ray diffraction, capacitance spectroscopy, in-plane photovoltaic, photoconductive measurements, DLTS techniques and SIMS.
  
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  Optical properties: The carrier recombination dynamics will be studied as a function of temperature by time-resolved photoluminescence or pump-probe transmission/reflection experiments. The comparison among samples with and without nitrogen will also provide information on the localised states and on the non-radiative channels associated to the presence of nitrogen or to the highly strained host matrix.
  
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  Electronic Properties: work has to be done with the view to explain and improve the devices operation. Very little is known about Auger recombination, and more generally about non-radiative processes involving electron-electron scattering, electron-phonon coupling in these materials. Those processes are known to decrease drastically the efficiency of laser diodes and they will be studied to design accurate and efficient working structures
  
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  Band structure: Band structure modifications due to nitrogen incorporation (bandgap energy, band offset, confined level energy, effective mass…) and its dependence on composition will be studied experimentally using optical spectroscopy, covering both inter-band optics and intra-band optics./
  

WP3 (a): Jointly executed research in devices & device Integration
This sub work package will address the novel OE devices and issues related to their integration.

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  Vertical Cavity Surface-Emitting Lasers (VCSELs), Vertical Cavity Semiconductor Optical Amplifiers (VCSOAs), These share advantages in design flexibility, novel functionality and minimised loss resulting from optical excitation in an undoped structure, especially important for wavelengths operation in the 1.2 - 1.6 m
  
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  EELs and SOAs operation in the 1.2 - 1.6 m as or pump lasers and amplifiers in optical communications networks.
  
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  Semiconductor Saturable Absorber Mirrors (SESAMs) for very-high repetition rate (~100 GHz) pulsed and potentially MEMS-tuneable sources
  
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  Vertical External Cavity Surface-Emitting Lasers (VECSELs) VECSELs (cavity length may be anything from ~100 m to tens of cm (tuneability may be achieved by MEMS-mounting of the external mirror). VECSEL devices in the 2 - 3 m range for applications in e.g. Free-Space Optical (FSO) communications
  
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  E-Absorption modulator and RCEPDs for 1.2-1.6 μm applications and (QWIPs)
  

WP4(a): Jointly executed research in theory and modelling
This sub work package will address the issues related to the theoretical understanding of the optical and electrical properties of dilute nitride materials in bulk form, and in quantum well (QW) and quantum dots (QD), and also to the development of simulation and modelling tools to explainthe behaviour of optical, optoelectronic and electronic devices fabricated in the dilute nitrides material system the novel OE devices and issues related to their integration.

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  Understanding the band structure of the GaInAsN/GaAs system and on evaluating gain spectra and threshold conditions for 1.3 μm lasers. And extend these to other range of materials and devices to be studied.
  
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  Understanding of band formation & band structure (with an especial focus on assessing the accuracy of the band anticrossing (BAC) model that is widely used for GaInAsN) and the effects of strain, defects, etc in the dilute nitrides, calculations of fundamental electronic properties, optical and electrical transport properties, and radiative and non-radiative recombination mechanisms,.
  
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  Fundamental theory in formulating device models; these must be accurately modeled, rigorously calibrated and tested against data from groups in the joint activity sub-work packages.
  
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  Constructing simulation tools for devices to be jointly studied in other clusters.
  
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  Calculations of optical properties of dilute nitrides in the visible and infra-red regions of the spectrum
  
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  Calculations of third-order nonlinear optical constants in order to assess the scope for all-optical signal processing components , e.g. SESAMs.
  

Calculations of Franz-Keldysh (FK) and Quantum-Confined Stark Effect (QCSE) in devices based on the material systems in jointly executed WP1(a)

B.4.3 Activities to spread excellence
We attach up most importance to “Spreading of Excellence” activities of the DiNAMITe project. Therefore, a specific work package, WP5, has been designated to coordinate these activities. WP5 is entitled “Activities for spreading excellence” and will be coordinated by Prof. Weimin M. Chen from LIU. I will have the following three sub-packages:
WP5.1 Training and Education

WP5.2 Dissemination and Networking

WP5.3 Integration toward a self-sufficient consortium after FP6 funding
Each sub-package will have a programme manager reporting to the coordinator of WP5.