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Quantum cascade lasers (QCLs) emitting at wavelengths as short as 2.63–2.65 μm are demonstrated. The InAs/AlSb QCL design was optimized to weaken carrier leakage into the L-valley by reducing coupling between the active InAs quantum wells. The lasers with HR-coated facets operated up to 175 K.

We study a Quantum Hot Electron Transistor, an original transistor made of InAs/AlSb heterostructures with high speed intrinsic transport. It is a unipolar vertical transport device, based on the concept of hot electron transistor. Devices using different heterostructure designs have been grown, processed and characterized. Both resonant and parasitic transport of electrons is studied by mean of the static output characteristics of the transistors. We demonstrated that a key parameter is the design and thickness of the collector barrier. For 15nm-thin barriers, we obtained static current gain of 5 associated to a base transit time of 140 fs.

We present a study of the structural and optical properties of a heterostructure emitting in the midinfrared. The structure consists of monolayerlike InSb quantum wells inserted in an InAs/GaSb superlattice (SL) matrix. X-ray diffraction and transmission electron microscopy analyses show a high structural quality of the structure. A strong emission line with a peak energy near 0.30 eV (3.5 mu m) is observed from the monolayerlike InSb. In order to identify the physical origin of this transition, excitation density and temperature dependent photoluminescence experiments have been performed on samples with different nominal InSb thicknesses and SL designs. The experimental results suggest a type II band alignment, with electrons localized in the conduction miniband of the InAs/GaSb SL matrix and holes localized in the monolayerlike InSb. This assignment is supported by the shift of InSb layer emission to lower energies when the SL design is changed, and by tight-binding calculations. (C) 2008 American Institute of Physics.

Quantum cascade lasers emitting at wavelengths as short as 2.75μm at 80K and 2.97μm near room temperature are demonstrated. Despite the small band gap of InAs, the laser performances are not affected by interband absorption. No effect of the L valley in InAs on quantum cascade laser performances is observed at 80K in these devices.

Demonstrated is laser emission between 2.5 and 3.5 µm from broad-area laser diodes with active zones made of InAs/GaSb short-period superlattices confined by AlGaAsSb guiding and cladding layers. A record threshold-current density of 20 A/cm2 is achieved at 95 K and 2.6 µm. Lasing below 3 µm is achieved up to room temperature, while it is limited at 160 K for longer wavelength owing to low carrier confinement. This demonstrates the potential of this material system for mid-infrared laser applications and shows that it is even more agile than previously considered.

Quantum cascade lasers emitting at wavelengths as short as 3.1–3.3μm are reported. Such high intersubband emission energies (up to 400meV) have been obtained thanks to the high conduction band offset of the InAs∕AlSb material system. The structures, grown by molecular beam epitaxy on InAs substrates, are based on the bound-to-continuum design and use a low loss plasmon enhanced waveguide consisting of n+-InAs cladding layers with InAs∕AlSb superlattice spacers surrounding the active zone. The lasers exhibit threshold current densities close to 3kA∕cm2 at 83K and operate in pulsed mode up to 240K.

Oxidation kinetics of Al-rich layers in ambient room conditions is investigated on cleaved mirrors of GaSb∕Ga1−xAlxAsSb (x=0.9–0.93) laser heterostructure. The measurements performed by atomic force microscopy demonstrate intensive growth of native oxide during the first two months with further saturation of the oxide thickness to about 1μm. In studies of the oxide cross section using additional cleavages perpendicular to the laser mirror, the volume of the oxidized part of the Al-rich layer is found to expand through elevations on the heterostructure mirror so that the height of the elevations reaches one-third of the total thickness of the oxide.

InAs/AlSb quantum cascade lasers emitting at 3.5–3.65 µm are demonstrated. The lasers employ a plasmon enhanced waveguide consisting of heavily doped n-InAs cladding layers and low doped InAs spacers. The maximum operation temperature is 200 and 140 K for lasers emitting near 3.65 and 3.5 µm, respectively. The present lasers' performances are limited by interband absorption in narrow gap InAs spacers.

International audience; The InAs/AlSb material system is a promising candidate for the development of short wavelength quantum cascade lasers because of the large conduction band offset of 2.1 eV. In this letter, we present a study of room temperature electroluminescence of InAs/AlSb quantum cascade structures as a function of the emission wavelength. Intersubband emission with a transition energy of 500 meV (λ=2.5 μm) has been obtained.

Quantum cascade lasers based on the InAs/AlSb material system have been realised. The optical confinement is obtained using a plasmon waveguide with n+-InAs cladding layers. In pulse mode the lasers emit close to 6.7 µm with a threshold current density of 5 kA/cm2 at 90K. The maximum operating temperature is 220K.

A study of the effects of the injected current and the thermal resistance on the tunability of antimonide-based diode lasers is presented. The studied diode lasers, emitting at around 2.3 µm, are dedicated to gas detection in the atmosphere, based on tunable-diode-laser absorption spectroscopy (TDLAS). This very useful technique requires, from the lasers, an emitted tunable wavelength able to cross a gas absorption line to detect the absorbed light. Typically a tuning rate of a few GHz/mA is sufficient to perform gas detection at atmospheric pressure (Vicet et al., 2002). It is then important to know and understand the tuning properties of the devices to achieve gas detection. They are very sensitive to thermal effects which are involved in all tuning processes. The lasers studied are shown to be well adapted to gas detection, paradoxically because of their large thermal resistance Rth which increases Joule heating, and mainly affects their tunability.

Mesa‐stripe injection lasers have been prepared from liquid phase epitaxial Ga0.88In0.12As0.10Sb0.90/Al0.47Ga0.53 As0.04Sb0.96 double heterostructures having an active zone of n‐type conductivity. These laser diodes could operate pulsed at heatsink temperatures up to 120 °C, and showed high characteristic temperature near ambient (T0≊110 K), comparable with theoretical value.

Narrow ridge 5 /spl mu/m-wide GaInSbAs/GaAlSbAs quantum well (QW) lasers emitting in the continuous wave (CW) regime at temperatures up to 130/spl deg/C have been fabricated. The CW threshold current varied between 20 and 35 mA at room temperature (RT). The lasers operated in the fundamental spatial mode and exhibited single longitudinal mode emission over a wide range of CW operation conditions. The emission wavelength increased from 2.26 /spl mu/m at RT up to 2.43 /spl mu/m at 124/spl deg/C. The CW output optical power reached 45 mW/facet at 22/spl deg/C and exceeded 10 mW/facet at 100/spl deg/C.

A continuous-wave regime, lasing near 2.2 /spl mu/m, has been achieved for single longitudinal mode GaInAsSb double heterostructure lasers mounted on a Peltier cooler. In the pulsed regime the lasers exhibited a characteristic temperature of the threshold current as high as 132 K at heatsink temperatures up to 60/spl deg/C.

Monolithic Sb-based vertical cavity surface emitting lasers (VCSELs) operating near 2.2 /spl mu/m at room temperature have been successfully fabricated and characterised. A pulsed output optical power of 20 mW has been achieved, the threshold current density being 2 kA/cm/sup 2/ for 200 /spl mu/m diameter devices. The entire structure was grown in a single growth run using molecular beam epitaxy.

Powerful mid-infrared (1.7-4.8 /spl mu/m) light emitting diodes were manufactured by liquid phase epitaxy using GaSb-InAs compounds. Their output optical power was enhanced up to 2-3.5 mW using symmetrical double heterostructures with large band offsets. These diodes can be used as narrow bandwidth emitters for cost-reduced setups for atmospheric pollution monitoring.

Laser diodes emitting at 2.36 µm at room temperature have been fabricated from a type-Il quantum-well heterostructure with an active region consisting of five Ga0.65In0.35As0.15Sb0.85 wells and GaSb barriers. A pulsed threshold current density of 305 A/cm2 has been obtained for an 820 µm-long-device at 23°C. The characteristic temperature T0 was found to be 55 K between –30 and 50°C, the differential quantum efficiency being 35% for 600 µm long lasers.

Laser emission is reported for the first time from a 10 monolayer-wide highly strained (3.2%) InAs single quantum well confined by Ga/sub 0.47/In/sub 0.53/As layers. At 80 K the emission spectrum of broad-area laser diodes is centred at 1.836 mu m, the threshold current-density is approximately 500 A/cm/sup 2/ and the characteristic temperature is T/sub 0/ approximately=30 K. CW operation is achieved up to 110 K with narrow-stripe devices but at shorter wavelength, due to increased losses and filling of the quantum-well energy levels.

The room-temperature vertical transport in InAs/AlSb and GaAs/AlAs short-period superlattices was studied. The influence of optical cavity on current-voltage characteristics was found in the range of both resonant and nonresonant tunneling. Possible explanations are suggested.

Sb-based materials rely on the GaSb, InAs, AlSb, InSb binary compounds and their quaternary or pentanary alloys (AlGaAsSb, GaInAsSb, AlGaInAsSb,.. ). This technology exhibits several distinctive properties as compared to other semiconductors: type-I to type-III band alignments, giant band offsets, low effective masses of electrons and holes, direct bandgaps between 0.15 and 1.7 eV. Conventional laser diodes (LDs) rely essentially on GaInAsSb type-I quantum wells (QWs) confined by AlGa(In)AsSb barrier layers. Low threshold currents and high T0 have been demonstrated between 1.5 and 3.4 µm. The AlGaInAsSb pentanary barrier is needed to extend the wavelength beyond 3 µm while keeping a type-I band alignment [3] even though it makes the epitaxial growth complex. Single mode operation has been achieved with both DFB lasers and VCSELs using the same active zone. At longer wavelength, interband cascade lasers (ICLs) based on GaInSb/InAs type-II p-n junctions stacked in series exhibit room temperature cw emission between 3.5 and 5 µm, including single mode operation of DFB lasers. At still longer wavelength InAs/AlSb quantum cascade lasers (QCLs) benefit from the low InAs effective mass and giant conduction band offset. High performance have been demonstrated all the way from 2.6 µm up to 25 µm, particularly at long wavelength which is an asset of this technology. The evolution toward smart, integrated, sensors requires integrating III-V optoelectronic devices with Si-based platforms. The epitaxial growth of III-V compounds on Si has thus been the focus of renewed attention for about a decade now. We have shown that the Si substrate preparation and the III-Sb nucleation on Si are crucial steps. This allowed us demonstrating a variety of epitaxially integrated optoelectronic devices such as laser diodes, photodetectors and the first ever QCL grown on Si. In this presentation we review the recent results obtained on the integration of antimonide-based QCLs epitaxially grown on Si substrates. We will show that this technology is very attractive for future III-V on Si integration, and we will discuss future integration schemes.

Emission of longitudinal optical phonons between the upper and the lower polariton branches has been observed in an intersubband electroluminescent device, operating in the strong coupling regime.

In last two decades QCL technology has proved itself as the most promising platform for many industrial and emerging applications such as gas sensing, environmental monitoring, LIDARs, free-space optical communications and many others. The investigations in topology resulted in the first QCL device that is robust to the structural defects [1] . At the same time, despite many valuable developments, there are still some unrevealed questions related to the carrier dynamics. One of them is the experimental investigations of the QCL turn-on delay time, which is a key parameter in many QCL-based technologies.

There is currently much activity toward the integration of mid-infrared semiconductor lasers on Si substrates for developing a variety of smart, compact, sensors based on Si-photonics integrated circuits. We review this rapidly-evolving research field, focusing on the epitaxial integration of antimonide lasers, the only technology covering the whole mid-to-far-infrared spectral range. We explain how a dedicated molecular-beam epitaxy strategy allows for achieving high-performance GaSb-based diode lasers, InAs/AlSb quantum cascade lasers, and InAs/GaInSb interband cascade lasers by direct growth on on-axis (001)Si substrates, whereas GaAs-on-Si or GaSb-on-Si layers grown by metal-organic vapor phase epitaxy in large capability epitaxy tools are suitable templates for antimonide laser overgrowth. We also show that etching the facets of antimonide lasers grown on Si is a viable approach in view of photonic integrated circuits. Remarkably, this review shows that while diode lasers are sensitive to residual crystal defects, the quantum cascade and interband cascade lasers grown on Si exhibit performances comparable to those of similar devices grown on their native substrates, due to their particular band structures and radiative recombination channels. Long device lifetimes have been extrapolated for interband cascade lasers. Finally, routes to be further explored are also presented.

Conference of Terahertz Emitters, Receivers, and Applications IV ; Conference Date: 25 August 2013 Through 26 August 2013; Conference Code:101016; International audience; CEA-Leti has developed a monolithic large focal plane array bolometric technology optimized for 2D real-time imaging in the terahertz range. Each pixel consists in a silicon microbolometer coupled to specific antennas and a resonant quarter-wavelength cavity. First prototypes of imaging arrays have been designed and manufactured for optimized sensing in the 1-3.5THz range where THz quantum cascade lasers are delivering high optical power. NEP in the order of 1 pW/sqrt(Hz) has been assessed at 2.5 THz. This paper reports the steps of this development, starting from the pixel level, to an array associated monolithically to its CMOS ROIC and finally a stand-alone camera. For each step, modeling, technological prototyping and experimental characterizations are presented.