Introduction

Photonics in communications has been the backbone of paradigm-changing advances such as fibre optics and broadband internet, and is set to continue this into the future with faster and higher capacity links. However, this growth in capability also brings more stringent requirements for confidentiality and data protection. In PROMIS, we will focus on developing novel materials for single photon sources and detectors that will enable quantum cryptography and secure communications. The integration of quantum communication protocols with present optical fiber technology requires single photon sources operating at 1.31μm and 1.55μm wavelengths, where optical losses and dispersion of silica fibers are minimal. The attainment of this goal relies on the development of reproducible nanostructuring techniques in materials emitting at the appropriate wavelengths.

Objectives:

• To develop new single photon sources for secure 1.31μ and 1.55μm telecom applications based on hydrogenated dilute nitride semiconductor nanostructures
• To fabricate nanoscale-LEDs based on laser-annealing of hydrogen irradiated (InGa)(AsN)
• To integrate single photon sources within a photonic crystal (PhC) microcavity

Partners involved in this Work Package

Collaborating Partners: UMR, NOTT, SHEFF, Tyndall-UCC, UCA, SGENIA, NAsP, ULANC

Projects in this Work Package

Project 1.1: Modelling of hydrogenated and dilute N semiconductors

Fellow:

Host: Tyndall-UCC

To provide relevant band structure information to support the design, development and analysis of dilute nitride metamorphic nanostructures. Tight-binding (TB) calculations will be undertaken to establish the impact of N on the electronic structure of GaSbN and InGaAsN layers grown on GaAs (WP1, WP3) and of InAsSbN grown on InAs/AlAsSb (WP4).

These will be used as input to k.p models to:

• support the design and analysis of single photon sources in collaboration with ROME & UMR (WP1),
• optimise the electronic and optical properties of GaSbN QDs for CPV solar cells grown by ULANC (WP3)
• design and optimise the emission characteristics of Type-II InAsSbN/InAs/AlAsSb structures grown by ULANC for mid-IR LED applications (WP4)

Project 1.2: Laser writing of nanoscale-LEDs based on dilute nitrides

Fellow:

Host: University of Rome

To create site-controlled nanoscale light emitting spots or ordered LED arrays by laser writing using hydrogenated (InGa)(AsN) p-i-n diodes, exploiting a new phenomenon discovered at NOTT [Adv. Mater. 22, 3176 (2010)]. The laser-driven diffusion of H to fabricate a nanoscale LED in dilute nitrides has never been reported before. This is a new concept of fundamental interest and technological importance. (InGa)(AsN) p-i-n structures will be grown in UMR & ULANC, fabricated in SHEFF and hydrogenated in ROME. Laser writing experiments will be conducted at NOTT informed by SEM and TEM (UCA). Materials development will be targeted to key wavelengths, i.e. 1.31 μm and 1.55 μm.

Project 1.3: Novel dilute-nitride (GaIn)(NAs)-based emitters epitaxially grown by MOVPE

Fellow:

Host: University of Marburg

MOVPE growth of (GaIn)(NAs)/GaAs p-i-n diode structures for site-controlled nanoscale light emitting spots or ordered LED arrays for emission wavelengths around 1.3 µm and 1.55µm. Specific low temperature non-equilibrium MOVPE growth studies also applying novel MO-III- as well as MO-V-compounds for improved, controlled incorporation of N in (GaIn)(NAs)-based heterostructures. Exploratory studies will be performed to integrate this concept on GaP-on-Si-template structures on (001) Si-substrate. Subsequent structuring will be fabricated in SHEFF, laser writing experiments will be performed in NOTT with hydrogenation experiments conducted in ROME with structural analysis of the processed samples by TEM in UCA.

Project 1.4: Hydrogenation of dilute nitrides for single photon emitters in photonic crystals

Fellow:

Host: University of Rome

The realization of single photon sources and their integration in photonic crystal (PhC) microcavities operating at 1.31 and 1.55 μm for telecom. (InGa)(AsN)/GaAs quantum wells will be grown by MOVPE at UMR and MBE at ULANC and characterized by photoluminescence at ROME and by transmission electron microscopy at UCA before and after hydrogen irradiation (ROME). Calculations at Tyndall-UCC will drive the sample design to reach the targeted energy gap. Hence, (i) achieve full N passivation by H, (ii) fabricate of site-, size-, and shape-controlled nanostructures emitting at the desired wavelengths. A synergic effort between Tyndall-UCC and ROME will engineer the positioning of QDs into PhC microcavities in order to emphasize and exploit solid-state electrodynamic effects.