A. Joullie

Low‐temperature phase diagram of the Ga‐As‐Sb system and liquid‐phase‐epitaxial growth of lattice‐matched GaAsSb on (100) InAs substrates

The liquidus and solidus in the Ga‐rich corner of the Ga‐As‐Sb system were determined by experiments using liquids of constant antimony concentration xLSb =0.0615. Evidence was obtained for a quite asymmetric solid‐phase miscibility gap. A theoretical phase diagram has been calculated on the basis of simple solution model. This diagram predicts the equilibrium conditions for the liquid‐phase epitaxy of lattice‐matched ternary layers on InAs substrates in the growth temperature domain 500–600u2009°C, but it gives a symmetric solid‐phase miscibility gap that is inconsistent with our experimental data. The actual conditions for exact lattice matching were experimentally determined by measurements on liquid‐phase‐epitaxial layers grown by the supercooling method on (100)‐oriented InAs. Flat and uniform mirrorlike epilayers were obtained using slight initial supercoolings (3–10u2009°C) within the range of relative lattice mismatch from −0.05% to +0.1%, which corresponds to positive mismatch (alayer>asubstrate) at the ...

A survey of new laser and detector structures for 3-5 μm midinfrared spectral range

The paper presents an overview of semiconductor laser and detector structures for the Mid-Infrared wavelength range (3 - 5 μm). Recent progresses in new laser systems are described: intersubband InAs/AlSb quantum cascade lasers (QCLs), interband type-II W lasers, and interband quantum cascade lasers (ICLs). All these laser structures employing AlSb, InAs, GaSb and related alloys have the potentiality to reach the challenge of room temperature operation in continuous wave for modern applications. The description of detector structures is focused on interband transition systems based on bulk InAs0.9Sb0.1, type-III InAs/GaSb superlattices or InSb/GaSb quantum dots.

Electrical characteristics of Au/p‐AlSb metal‐insulator‐semiconductor Schottky diodes

Metal‐insulator‐semiconductor Schottky barrier diodes have been prepared on p‐type bulk AlSb by evaporating gold on a chemically etched (100) AlSb surface. The existence of an oxide‐rich interfacial layer between gold and AlSb of ∼70 A thickness was shown by means of secondary ion mass spectrometry analysis. The current‐voltage (I‐V) and capacitance‐voltage (C‐V) characteristics were measured. The barrier height qφBp(0) obtained from the Richardson plot log(Is/T2) vs (1/nT) is 0.71 eV. The 1/C2‐vs‐V plot was not a straight line. From the ideality factor at room temperature (n=1.4) and the intercept voltage V0 of the 1/C2‐vs‐V curve (V0=1.2 V), a density Ds of interface states was evaluated around 5×1011 cm−2 eV−1.

On spectral line broadening in quantum-well heterostructure lasers

Theoretical analysis of the emission line broadening in quantum-well lasers is carried out taking into account the Coulomb interaction of current carriers in the approach of two-dimensional electron-hole gas. The principal idea of the used method consists in the determination by means of the perturbation theory for many-body systems the functional behavior of tails of the emission line and in the subsequent extrapolation of the central part of the line according to a normalization requirement. Based on the obtained in the parabolic band approximation analytical shape function for the homogeneously broadened spectral line, the influence of various factors on the optical spectrum is analyzed. An explanation of the experimental data, including the spectral line asymmetry and the linewidth change versus temperature and power excitation, is given. Results of the numerical calculations are presented for quantum-well heterostructure laser diodes in the GaInAsSb-AlGaAsSb-GaSb system. Spectra of luminescence and gain in dependence on the quantum well width, temperature, and excitation level are examined. Spectrum transformation in the long-wavelength range and tuning curves for the GaSb-based laser emitters are also discussed. New possibility to overlap the spectral emission diapason of 2.2-2.9 μm is examined due to asymmetric multiple-quantum-well heterostructure configuration of the active region.

Self-consistent calculations of the energy and tunable emission spectra of doping superlattices

Based on the developed method of self-consistent calculations the results of description of tunable optical spectra versus temperature and excitation level for the GaSb doping superlattices of different design are presented. Account of the appearing tails of the density of states allows describing the long-wavelength edges and shape transformation in the spectra of absorption, gain, and luminescence and peculiarities in the optical transitions characteristics. Possible laser diode structures with n-i-p-i crystals in the active region are suggested including ordinary and δ-doped superlattices. Effects of tunable lasing are examined and ways for control of the radiation wavelength are discussed.

PREPARATION AND NOISE CHARACTERIZATION OF Ga Al (As) Sb DIFFUSED P + N DIODES

GaAlAsSB / GaSb is a suitable system for fiber optical communications in the long wavelength detection (1.3 - 1.6 μm). GaAlSb and GaAlAsSb MESA p + n photodiodes were prepared by LPE and Zinc diffusion. The noise currents of both devices, measured in the different polarization range, are shot noise, 1/f noise, G.R. noise and tunneling component multiplication noise.

Limitation des performances des photodétecteurs à avalanche GaAIAsSb par effet tunnel

AnalyseLes liaisons optiques à grande distance de haut débit exigent des détecteurs rapides à faible bruit adaptés aux fenêtres de transmission 1,3 ou 1,55 μm des fibres optiques à verre de silice. Le système GaAlAsSb/GaSb peut répondre à ce besoin, et des photodiodes ont été récemment réalisées avec, comme zone active, le ternaire GaAlSb ou bien le quaternaire GaAlAsSb qui offre l’avantage d’avoir un paramètre de maille accordé sur celui du substrat GaSb [1 à 6]. Malheureusement, ce système a toujours présenté des courants d’obscurité élevés attribués soit à des courants de surface [4], soit à des courants de type tunnel [6]. Dans cet article, les auteurs montrent que la composante du courant inverse à l’obscurité est effectivement dominée dans une large gamme de polarisations par un effet tunnel bande à bande, ou assisté par pièges, ce qui limite la valeur du facteur de multiplication optimal et augmente la puissance équivalente du bruit.AbstractThe high rate long distance fiber optical communications require rapid low noise detectors adapted to wavelengths 1.3 or 1.55 μm. GaAlAsSb/GaSb is a suitable system for this need. Recently, the authors have obtained photodiodes with ternary GaAlSb or quaternary GaAl AsSb as an active layer. Quaternary alloys were latticematched to GaSb substrate [1–6]. But, this system presented large reverse dark currents attributed either to surface currents or tunneling currents [6]. In this paper, we prove that in a large range of polarization the reverse dark current is dominated by band to band tunneling or defect assisted tunneling. This limits the value of the optimum multiplication factor and increases the noise equivalent power.