P. Grech

Continuous-wave operation above room temperature of GaSb-based laser diodes grown on Si

We have investigated specifically designed GaSb-based laser diodes epitaxially grown on a Si substrate. We demonstrate continuous-wave operation of these laser diodes emitting near 2 μm up to 35 °C with several mW/facet output powers, limited by our experimental setup. Our results open the way to direct monolithic III-V/Si integration.

Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes

In this paper, we studied wet chemical etching fabrication of the InAs/GaSb superlattice mesa photodiode for the mid-infrared region. The details of the wet chemical etchants used for the device process are presented. The etching solution is based on orthophosphoric acid (H3PO4), citric acid (C6H8O7) and H2O2, followed by chemical polishing with the sodium hypochlorite (NaClO) solution and protection with photoresist polymerized. The photodiode performance is evaluated by current?voltage measurements. The zero-bias resistance area product R0A above 4 ? 105 ? cm2 at 77 K is reported. The device did not show dark current degradation at 77 K after exposition during 3 weeks to the ambient air.

Low-threshold GaInAsSb/AlGaAsSb quantum well laser diodes emitting near 2.3 µm

We report on low-threshold high-power quantum well diode lasers emitting near 2.3 µm based on the GaInAsSb/AlGaAsSb system. The threshold current density per quantum well is as low as 63 A cm−2. A maximum output power of 540 mW at 293 K in the continuous wave regime has been achieved.

Room-temperature operation of a 2.25 μm electrically pumped laser fabricated on a silicon substrate

We report on a GaSb-based type-I laser structure grown by molecular beam epitaxy on a (001) silicon substrate. A thin AlSb nucleation layer followed by a 1 μm thick GaSb buffer layer was used to accommodate the very large lattice mismatch existing with the silicon substrate. Processed devices with mesa geometry exhibited laser operation in pulsed mode with a duty cycle up to 10% at room temperature.

GaInSb/AlGaAsSb strained quantum well semiconductor lasers for 1.55 m operation

Gallium antimonide and related compounds are promising materials for fabricating monolithic vertical cavity semiconductor lasers operating at telecommunications wavelengths. With that aim active layers based on multiquantum wells have been evaluated by means of a separate-confinement laser diode structure grown on a GaSb substrate by molecular beam epitaxy. Owing to optimization of the growing process, for the well/barrier structure, laser emission at 1.4 m has been obtained at 80 K with a threshold current as low as 15 mA for a 640 m long and 15 m wide mesa stripe structure. At room temperature laser emission occurred at 1.55 m with a pulsed threshold current density of 4 kA according to the measured characteristic temperature of 50 K. In a first attempt such an active layer has been included in a 1.5 m microcavity involving antimonide Bragg mirrors.

Room-Temperature Continuous-Wave Operation of 2.3-

Room-temperature continuous-wave (CW) operation of GaSb-based monolithic microcavity vertical-cavity surface-emitting lasers operating near 2.3 mum is presented. These devices were composed of two n-doped AlAsSb-GaSb Bragg mirrors, a type-I GaInAsSb-AlGaAsSb multiquantum-well active region, and an n++-InAsSb/p++-GaSb tunnel junction. CW laser operation was observed up to 294 K. A CW threshold current density as low as 1.1 kA ldr cm-2 was obtained at 284 K for 60-mum-diameter devices (20-mum-diameter emitting area).

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The molecular beam epitaxy growth of A1AsSb/A10.04Ga0.96AsSb distributed Bragg reflectors lattice-matched to InP is studied. The fabrication and characterization of two such reflectors are reported. Fine structural and optical properties of these samples are investigated using double crystal X-ray diffraction, scanning electron microscopy and reflectivity measurements. Main device performances are a 260 nm wide stop-band centred at 1.55 μm with a maximum reflectivity of 90% for the first 8.5 pairs Bragg reflector while the second 15.5 pairs reflector have allowed an improved maximum reflectivity exceeding 96% at 1.6 μm with a stop-band of 220 nm. As a major result, a new type of surface defects is observed on the A1GaAsSb/A1AsSb Bragg reflector surface. Planar and cross-sectional microscopic observation has revealed that defects are initiated from the reflector-substrate interface. The formation of these defects are discussed and it has been related to InAs islands that appear during the in situ InP-substrate oxide desorption procedure.

m Sb-Based Electrically Pumped Monolithic Vertical-Cavity Lasers

Type-I quantum-well laser diodes with an active region constituted of GaInAsSb-AlGaInAsSb are reported. Broad-area lasers have demonstrated a threshold current density of 255 A/cm2 at room temperature. Distributed-feedback lasers have been operated in the continuous-wave regime at 20°C with a wavelength of 3.06 μm, a threshold current of 54 mA, and an output power of 6 mW.

Molecular beam epitaxy growth and characterizations of AlGaAsSb/AlAsSb Bragg reflectors on InP

Diode lasers operating at room temperature with an emission wavelength of have been fabricated from compressively strained multiple-quantum-well structures grown by molecular beam epitaxy. Ridge waveguide lasers long exhibited an RT current threshold of 500 mA, optical power efficiency of /facet and a differential quantum efficiency of 14.5%. A pulsed threshold current density less than with a characteristic temperature have been achieved for broad mesa devices. The laser structure, which has a type-II band alignment at the well-barrier interface, showed an internal efficiency , controlled by the electron-hole wavefunction overlap at the interface.

Laser Diodes for Gas Sensing Emitting at 3.06

In this paper, the process of fabrication of GaSb-based electrically injected resonant-cavity LEDs near 2.3 mum is detailed. The electrical and optical properties of these diodes operating in continuous wave at room temperature are also presented. The different tested monolithic structures have similar designs with two doped AlAsSb/GaSb Bragg mirrors and an active region with eight GaInAsSb quantum wells. Performances of devices containing or not an n++-InAsSb/p++-GaSb tunnel junction (TJ) can be compared. The large improvements of electrical resistance as well as output power, observed when a TJ is included, demonstrate all the advantages to use such a technology for the realization of electrically injected vertical cavity structures emitting in the mid-IR on GaSb substrate.