H. L'Haridon

Optical Activation of Er3+ Implanted in Silicon by Oxygen Impurities

Luminescence spectra and SIMS measurements of Er-doped silicon are presented in this paper. Luminescence was found to be stronger in Czochralski-grown Si crystals, known to contain up to 1018 cm-3 of oxygen center. Direct role played by oxygen impurities in the optical activation of the 1.54 µm luminescence was demonstrated by implanting oxygen into Er implanted layers in silicon at concentrations comparable to those of Er. Possible mechanisms of enhancement of photoluminescence are discussed.

High photoluminescence efficiency of InAs/InP self-assembled quantum dots emitting at 1.5 -

Self-assembled InAs quantum dots emitting at 1.5 - with high efficiency have been grown by GSMBE on InP. One of the most important properties of quantum dots is the conservation of high radiative recombination efficiency at room temperature as opposed to the case of quantum wells. This property has been evidenced on carefully grown quantum dots by photoluminescence measurements between 2 K and 300 K.

Structural aspects of the growth of InAs islands on InP substrate

Abstract Several samples with InAs deposit from 1.2 to 4 monolayers (ML) have been grown on InP(001) by gas source molecular beam epitaxy and examined by photoluminescence, transmission electron microscopy and Raman spectroscopy. Coherent InAs islands due to the Stransky-Krastanov growth mode has been achieved above 1.5 ML. Two different island growth modes depending on the total InAs coverage have been identified. From 1.5 to 2 ML, the average island height is 7 nm, while above 2.5 ML it is only 3–4 nm. The island volume is also decreased by a factor 5. Below 2 ML, the dots are randomly distributed, while above 2.5 ML there is a typical distance of 40 nm independent on the island density. The relationship between island size, island shape and island spatial distribution is discussed. The islands are more elastically relaxed in the first growth mode than in the second one. The existence of two growth modes is attributed to the major role of the substrate distortion in the elastic relaxation mechanism.

Erbium implanted in III-V materials

Erbium impurities were implanted in binary, ternary and quaternary III–V semiconductors. The main erbium emission centered at 1.54 µm is an invariant for III–V semiconductors having a band gap energy higher than the intrashell transition energy of Er 4f electrons (0.805 eV). The erbium emission is independent of the emission temperature from 2 K to 300 K.

Epitaxial liftoff microcavities for 1.55-μm quantum-well spatial light modulators

Microcavities operating at 1.55 /spl mu/m have been realized according to the epitaxial liftoff (ELO) technique. The process is described and characterized. No significant variation of the optical properties of the grafted devices has been found. The technique is then applied to a spatial light modulator made by inserting a 3-/spl mu/m multiple-quantum-well device in a short asymmetric Fabry-Perot microcavity. An enhancement by a factor 1000 of the performances of the switching component is obtained. The input diffraction efficiency reaches 2% in a degenerated four wave mixing configuration with a pulse energy of 1 /spl mu/J/cm/sup 2/ and without any applied electric field.

The effect of the growth procedure and the InAs amount on the formation of strain-induced islands in the InAs/InP(001) system

Abstract Using the strain-induced 2D–3D transition, InAs dots have been grown on InP(001) by gas source molecular beam epitaxy and examined by transmission electron microscopy. Various InAs amounts have been deposited, and the islands were either capped or uncapped. Small strained islands, large strained ones, and plastically relaxed ones were observed, showing that different degrees of relaxation have been achieved depending on these growth parameters. Comparison of capped and uncapped islands showed that the island evolution was stopped by the island coverage. The comparison of islands obtained for different deposited amounts suggests that the inter-island interactions can delay the island evolution towards a higher degree of relaxation. Finally, the elastic interaction between islands was calculated by the finite-element method.

Simulation and photoluminescence characterization of transverse electric-transverse magnetic emission of strained Ga0.47In0.53As/Ga0.62In0.38As superlattices

Abstract Optimization of the growth conditions of strained-layer superlattices for polarization-insensitive semiconductor optical amplifiers is reported. The quality of the structure is assessed by transmission electron microscopy studies. Polarized room temperature photoluminescence is shown to be a powerful tool to investigate the complex band structure of such structures. The comparison of experimental and simulated photoluminescence spectra reveals a very good agreement.

Multiple quantum well optically addressed spatial light modulators operating at 1.55 µm with high diffraction efficiency and high sensitivity

New results on GaInAs-GaInAsP multiple quantum well (MQW) spatial light modulators are reported. The device structure consists of 50 periods of MQW enclosed in an asymmetric Fabry-Perot (FP) micro-cavity 80-98%. An input diffraction efficiency of 2% is measured in a degenerate four-wave-mixing configuration with a pulse energy of 1 µJ cm-2, in comparison with only 2×10-3% measured on the reference device where the front reflectivity of the FP is close to zero: embedding an MQW device in a short micro-cavity enhances the diffraction efficiency by a factor of 1000.

Multiple quantum well spatial light modulators operating at 1.55 μm with high diffraction efficiency and high sensitivity

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Growth study of self-assembled Ga/sub x/In/sub 1-x/As islands on InP

The growth of self-assembled tridimensional (3D) islands has been increasingly studied lately to produce quantum dots. This technique is the most promising for fundamental studies in a zero dimensional semiconductor system as well as for micro-optoelectronics devices applications, such as lasers and memory devices. The use of 3D-islands has however been limited by the lack of control of their size uniformity and of regular organization on the substrate surface. We proposed to use InAs 3D islands as trapping zones in photorefractive structures on InP substrates. For this application, we need islands which deeply confine the carriers for an efficient trapping mechanism. The islands also have to be dense enough to avoid any lateral diffusion of the carriers. In this work, we study the growth of InAs and Ga/sub x/In/sub 1-x/As layers compressively strained on InP, in order to produce 3D islands which fulfil these requirements. The optical and structural properties of the islands have been characterized by photoluminescence (PL) and atomic force microscopy (AFM) respectively. We have been able to correlate the optical and structural properties of the islands by performing the PL and AFM measurements on the same structure for InAs and Ga/sub x/In/sub 1-x/As islands. Finally, we compare the growth of Ga/sub x/In/sub 1-x/As islands on (100) and (311)B InP substrates, for two Ga/sub x/In/sub 1-x/As compositions.