Inorganic Semiconductors

Our objective here at CNR-Nanotec is the development of new semiconducting materials and nanostructures representing the foundation of more efficient, high performance, low power consumption optoelectronics and micro/nanoelectronics devices. To that purpose, we comprehensively study and engineer growth dynamics and structural features in inorganic semiconducting compounds of different families, to enable innovative optical, magnetic and electronic properties which can be applied to the fields of photonics, electronics, sensing, or biotechnology. A wide range of materials and related applications is covered by the center, thanks to the availability of material-driven facilities and to the close synergy with the other platforms of the institute and with external national and international collaborations.

The main topics are:

  1. III-N Heterostructures
  2. III-V Semiconductors
  3. Si-based thin Films and Its Alloys

III-N Heterostructures

Gallium nitride, GaN, ant its alloys with aluminum, AlGaN, and indium, InGaN, and the quaternary InGaAlN represent a class of semiconductors with properties of wide and direct band gap (tunable from the deep UV to the NIR), high break-down voltage, large critical electric field, and high thermal conductivity. Applications of these compounds encompass next generation of high frequency/high power transistors and optoelectronics devices, such as deep-blue and ultraviolet LEDs, lasers and photodetectors. Furthermore, the chemical and mechanical robustness of these compounds allows operation in harsh conditions, thus opening several possibilities for sensing in drastic environments. Our III-Ns technology is  based on metal organic chemical vapour deposition (MOCVD) growth combined with suitable nanofabrication tools  of Chlorine-chemistry deep etching and deep UV optical lithography.

Research topics:

  1. Create recipes for oxide removal and substrate preparations enabling better control of the surface in initiating epitaxy on various substrates (sapphire, SiC, Si, GaN, oxides-ZnO, LAO,..)
  2. Develop and understand growth processes to improve materials quality
  3. Growth of high Al-containing (and high-In) III-N Materials (InAlN, AlGaN, InAlGaN,..)
  4. Increase the IQE of blue and green InGaN HB-LEDs via the use of quantum heterostructures fabricated on the non-polar a- and m-planes

Strategies

  1. Development of new processes combining MOCVD and MBE with plasma technologies
  2. Processing and modulation of interfaces in multilayer structures
  3. In situ real time multidiagnostics approach to control and understand growth processes
  4. Investigating the process-properties-functionality interplay through extensive characterization

III-V Semiconductors

Our research aims at enlarging the current palette of technological semiconductors with new alloys and quantum confined nanostructures to respond to the continuous need of new materials with tunable properties that add flexibility to the design  and performance of optoelectronic and electronic devices.

Research topics:

  1. Investigation of relevant growth mechanisms by molecular beam epitaxy (MBE) governing the formation of self-assembled InAs/GaAs quantum dots (QDs) and their structural properties for applications in photonics, telecommunications and solar cells.
  2. Novel growth strategies for the Bi-containing  semiconductors of GaAsPBi, GaAsSbBi, which are  exciting candidates for next generation optoelectronic and  spintronic devices
  3. MOCVDgrowth of nanostructures of InN, InP, by VLS (Vapour-Liquid-Solid phase Epitaxy)
  4. III-Vs (GaAs, InAs, InP, GaP) surface functionalization towards achieving biological and chemical sensing applications

Si-based thin Films and Its Alloys

Silicon, in all its forms of crystalline, microcrystalline, nanocrystalline and amorphous is the foundation of the microelectronics and photovoltaics. Capabilities of silicon can still be enlarged by “bandgap enginnering” using Si-based alloys such as silicon germanium (Si:Ge), silicon carbon (Si:C) providing a tunable band gap from <1eV for Si:Ge to >2.5eV for Si:C extending to dielectrics of silicon nitrides Si:N and silicon dioxide SiO2. The research covers the synthesis, characterization, modelling, device performance in different fileds, photovoltaics, electronics.

Research topics:

  1. Plasmochemical deposition of amorphous and microcrystalline silicon by PECVD using SiF4-H2-He and SiH4-H2-He as precursors
  2. PECVD deposition assisted by Sputtering of nanostructured Er-doped Si thin films
  3. Study of their optical, compositional and electrical properties and correlation between bonding configuration, growth dynamics, film nanostructure and optical properties

Strategies:

  1. Development and understanding of plasma processes in order to improve materials quality
  2. Processing of substrates and optimization of interfaces in multilayer structures
  3. Optimization and understanding of the correlation between the nanostructure and optical properties for the optimization of devices
  4. In situ real time multidiagnostics approach to control and understand growth processes.

Facilities & Labs

Nanotec @ Lecce

Nanotec @ URT Bari

People

passaseo

Adriana

Passaseo

CNR Senior Researcher

massimo_cuscuna

Massimo

Cuscunà

CNR Technologist

espositomarcoMarco

Esposito

Associate PhD Student

Giovanni_Bruno

Giovanni

Bruno

CNR Director of Research

VittoriannaTasco

Vittorianna

Tasco

CNR Researcher

Iolena_tarantiniIolena

Tarantini

Associate Technician

Maria_LosurdoMaria

Losurdo

CNR Director of Research

mariamichelgiangregorio_researcherMaria Michela

Giangregorio

CNR Researcher

Publications

  1. W. Jiao, W. Kong, J. Li, K. Collar, T.H. Kim, M. Losurdo, A.S. Brown, Characterization of MBE-grown InAlN/GaN heterotructure valence band offset with varying In composition.AIP Advances, 6, 0352011 (2016); DOI: 10.1063/1.4944502
  2. W. Jiao, W. Kong, J. Li, K. Collar, T.H. Kim, M. Losurdo, A.S. Brown, The characteristics of MBE-grown InAlN/GaN surface states. Appl. Phys. Lett. 109, 082103 (2016); DOI: 10.1063/1.4961583
  3. A. Creti, V. Tasco, A. Cola, G. Montagna, I. Tarantini, A. Salhi, A. Al-Muhanna, A. Passaseo, M. Lomascolo, Role of charge separation on two-step two photon absorption in InAs/GaAs quantum dot intermediate band solar cells. Appl. Phys. Lett. 108, 063901 (2016). DOI: 10.1063/1.4941793
  4. W. Kong, A.T. Roberts, W.Y. Jiao, J. Fourmelle, T.H. Kim, M. Losurdo, H.O. Everitt, A.S. Brown, Room temperature Ultraviolet B emision from InAlGaN films synthesized by plasma-assisted molecular beam epitaxy, Appl. Phys. Lett. 107, 132102 (2015). DOI: 10.1063/1.4931942
  5. V. Tasco, M. Usman, M. De Giorgi, A. Passaseo, Tuning of polarization sensitivity in closely stacked trilayer InAs/GaAs quantum dots induced by overgrowth dynamics.  Nanotechnology, 25,  5 (2014). DOI: 10.1088/0957-4484/25/5/055207
  6. M. Forghani, Y. Guan, M. Losurdo, GaAs1-y-zPyBiz, an alternative reduced bandgap alloy system lattice-matched to GaAs,Appl. Phys. Lett. 105, 111101(2014). DOI: 10.1063/1.4895116
  7. W. Kong, A. Mohnta, A.T. Roberts, W.Y. Jiao, J. Fournelle, T.H. Kim, M. Losurdo, H.O. Everitt, A.S. Brown, Room temperature photoluminescence from InxAl(1-x)N films deposited by plasma-assisted molecular beam epitaxy,Appl. Phys. Lett. 105, 132101 (2014). DOI: 10.1063/1.4896849
  8. D. A. Cullen, D.J. Smith, A. Passaseo, V. Tasco, A. Stocco, M. Meneghini, G. Meneghesso, E. Zanoni, Electroluminescence and transmission electron microscopy characterization of reverse-biased AlGaN/GaN devices,Device and Materials Reliability, IEEE Transactions, 13, 1, 126-135(2013). DOI: 10.1109/TDMR.2012.2221464
  9. M. Usman, V Tasco, MT Todaro, M De Giorgi, EP O’Reilly, G Klimeck, A Passaseo, The polarization response in InAs quantum dots: theoretical correlation between composition and electronic properties, Nanotechnology, 23, 16 (2012). DOI: 10.1088/0957-4484/23/16/165202
  10. D. Munoz-Martin, Y. Chen, M. Morales, J. J. Garcia-Ballesteros, J. Carabe, J.J. Gandia, J. D. Santos, M. Losurdo, G. Bruno, C. Molpeceres, “Parameterization of a-Si crystallization by continuous-wave green laser irradiation: from single spot to large area” J. Photon. Energy 5, 053086 (2015). DOI: 10.1117/1.JPE.5.053086

Patents

Projects

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