G. Deligeorgis

Foundation for Research and Technology Hellas

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Z. Hatzopoulos

FORTH Institute of Electronic Structure and Laser

D. Neculoiu

Universitatea Națională de Știință și Tehnologie Politehnica București

A. Georgakilas

FORTH Institute of Electronic Structure and Laser

Mircea Dragoman

National Institute for Research and Development in Microtechnologies

P. G. Savvidis

FORTH Institute of Electronic Structure and Laser

N. T. Pelekanos

University of Crete

Alina Cismaru

National Institute for Research and Development in Microtechnologies

R. Plana

Assystem (France)

E. Aperathitis

Foundation for Research and Technology Hellas

A. Müller

National Institute for Research and Development in Microtechnologies

Cooperative Institutions

Foundation for Research and Technology Hellas

University of Crete

FORTH Institute of Electronic Structure and Laser

Centre National de la Recherche Scientifique

National Institute for Research and Development in Microtechnologies

Aristotle University of Thessaloniki

FORTH Institute of Chemical Engineering Sciences

University of Cambridge

University of Southampton

Université Toulouse III - Paul Sabatier

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Properties of GaAs/Si heterostructure material fabricated by low temperature wafer bonding using a spin-on-glass intermediate layer

G. Deligeorgis Spyros Gallis M. Androulidaki D. Cengher Z. Hatzopoulos

MBE grown GaAs wafers were bonded, using spin on glass, on CMOS and plain Si wafers, GaAs substrate was removed to provide a thin layer of GaAs material, on top of silicon, for device processing. Structural investigation of the GaAs filmoil was done using TEM. Material quality was further investigated using photoluminescence measurements. Built in strain was measured using photoreflectance measurements for a range of temperatures and compared to that of an epitaxially grown GaAs on Si. High quality material that is nearly stress free at room temperature was successfully integrated with Si using the proposed method.

Wafer Bonding

Atmospheric temperature range

10.1109/sim.2002.1242739

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Citations (3)

Piezoelectric effect on the lasing characteristics of (111)B InGaAs/AlGaAs laser diodes

AIP conference proceedings (2005)

G. Deligeorgis

In this work we investigate both experimentally and theoretically the effect of the piezoelectric (PZ) field on the lasing characteristics of InGaAs (111)B quantum wells. We show that, under certain conditions, the existence of the PZ field can be beneficial and lead to substantial threshold current reduction in (111)‐grown InGaAs/AlGaAs laser diodes, compared to their (100) counterparts.

Indium gallium arsenide

10.1063/1.1994698

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Intervalley scattering of excitons and trions in monolayer WSe$_{2}$ under strong excitation

arXiv (Cornell University) (2015)

Anatolie Mitioglu Ł. Kłopotowski D. K. Maude G. Deligeorgis S. Anghel

Monolayer transition metal dichalcogenides offer the possibility of optical control of the valley degree of freedom. In order to asses the potential of these materials in applications, detailed knowledge of the valley dynamics is essential. In this work, we apply low temperature time-resolved photoluminescence (PL) measurements to investigate exciton valley relaxation dynamics and, in particular, its behavior under strong excitation. At the lowest excitation powers the inter valley scattering time is $\simeq 50$ ps, but shortens by more than a factor of two at the highest powers. We attribute this acceleration to either heating of the exciton system or the presence of a dense exciton gas, which could influence the exciton valley properties. Furthermore, we analyze the PL dynamics of excitons and trions. We find that the PL decays for all peaks are bi-exponential and approximately independent of the excitation power. We attribute the short decay to radiative recombination and escape to a reservoir of dark states. The long decay is ascribed to a transfer of excitons back from the reservoir. For the first time, we evaluate the exciton PL decay time of $\simeq$ 10 ps. The latter process is valley-conserving and occurs on a timescale of $\simeq$ 50 ps.

Exponential decay

10.48550/arxiv.1507.00496

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GaAs membrane supported millimeter wave circuits

A. Müller Г. Константинидис D. Neculoiu M. Lagadas G. Deligeorgis

The paper presents the author's contributions towards the development of the millimeter wave circuits based on GaAs micromachining. The manufacturing and characterisation of low losses, GaAs membrane supported band pass filters for 38 GHz, 45 GHz and 77 GHz as well as a fully integrated millimeter wave receiver structure having the antenna and the detecting Schottky diode on the same GaAs membrane are presented.

Extremely high frequency

10.1109/smicnd.2003.1251344

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Comparison of InGaAs/InAlAs electroabsorption modulator structures on (100) and (111) InP substrates

Materials Science and Engineering B (1999)

C. Michelakis A. Georgakilas M. Androulidaki K Harteros G. Deligeorgis

Vicinal

Photocurrent

Absorption edge

Crystal (programming language)

10.1016/s0921-5107(99)00104-x

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A High-Gain CNTFET-Based LNA Developed Using a Compact Design-Oriented Device Model

Electronics (2021)

Paolo Crippa Giorgio Biagetti Claudio Turchetti Laura Falaschetti Davide Mencarelli

Recently, carbon nanotube field-effect transistors (CNTFETs) have attracted wide attention as promising candidates for components in the next generation of electronic devices. In particular CNTFET-based RF devices and circuits show superior performance to those built with silicon FETs since they are able to obtain higher power-gain and cut-off frequency at lower power dissipation. The aim of this paper is to present a compact, design-oriented model of CNTFETs that is able to ease the development of a complete amplifier. As a case study, the detailed design of a high-gain CNTFET-based broadband inductorless LNA is presented.

10.3390/electronics10222835

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Citations (3)

Room temperature GaAs exciton-polariton light emitting diode

Applied Physics Letters (2009)

S. I. Tsintzos P. G. Savvidis G. Deligeorgis Z. Hatzopoulos N. T. Pelekanos

Room temperature GaAs polariton emission is demonstrated under electrical injection. Temperature and angle-resolved electroluminescence measurements on a polariton light emitting diode clearly show the persistence of Rabi splitting and anticrossing behavior at temperatures as high as 315 K. We show that by increasing the number of quantum wells in the structure, the cutoff temperature for the strong coupling regime can be pushed beyond room temperature, in good agreement with theory. Our results suggest that optimally designed GaAs microcavities are perfectly suited for room temperature polaritronics.

10.1063/1.3082093

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Citations (45)

Influence of polarization field on the lasing properties of III-nitride quantum wells

Physica E Low-dimensional Systems and Nanostructures (2006)

G. E. Dialynas G. Deligeorgis Matthew Zervos N. T. Pelekanos

Poisson's equation

10.1016/j.physe.2005.12.153

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Millimeterwave Schottky diode on grapene monolayer via asymmetric metal contacts

Journal of Applied Physics (2012)

Mircea Dragoman G. Deligeorgis A. Müller Alina Cismaru D. Neculoiu

The paper presents the experiments regarding a Schottky diode fabricated on a graphene monolayer using asymmetric metallic contacts. The current is in the mA range, which is with orders of magnitude higher than for reported Schottky diodes prepared on graphene bilayers or related graphene materials. Moreover, this device exhibits a DC controllable phase shift of more than 20 degrees in the range 40–65 GHz.

Metal–semiconductor junction

10.1063/1.4759347

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Citations (9)

Reduced threshold current in (111)B grown InGaAs∕AlGaAs laser diodes: The positive role of piezoelectric effect

Applied Physics Letters (2007)

G. Deligeorgis G. E. Dialynas Z. Hatzopoulos N. T. Pelekanos

The authors demonstrate that (111)B grown InGaAs∕AlGaAs laser diodes outperform their (100) counterparts, in terms of lower threshold currents observed for all temperature and cavity lengths tested. A low temperature threshold current density as low as 15A∕cm2 has been observed in (111)B grown devices, whereas identical (100) laser diodes exhibited threshold in the range of 30–40A∕cm2. The comparison of experimental findings with a Poisson-Schrödinger self-consistent model reveals that the improved performance of the (111)B devices is attributed to the piezoelectric field present in the (111)B In0.1Ga0.9As active quantum well as well as to the different heavy hole effective masses in the (111)B configuration.

10.1063/1.2716214

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Citations (5)