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ABSTRACT: Dislocations induced by scratching produce deep narrow spikes of zinc diffused in gallium arsenide. Density of defects formed locally increases zinc diffusion coefficient. Enhancements by factor of 6 have been observed. Technique works for other dopants than zinc and for other semiconductors besides GaAs.
07/1980;
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ABSTRACT: This paper reviews the major factors bearing on the reliability of (AlGa)As CW laser diodes. The degradation modes of facet mirror damage, contact degradation, and internal damage are discussed in terms of our present knowledge of their effects on device performance, their origin, and their reduction or elimination. Detailed results are presented for oxide-defined stripe-contact lasers and, although reliability results are a strong function of fabrication technology, there are many issues common to all fabrication technologies, and these are emphasized. Lasers have been operated in our laboratory for more than 40 000 h with extrapolations indicating a median time to failure (MTTF) between 10<sup>5</sup>and 10<sup>6</sup>h. In these lasers both facet damage and contact degradation appear to be under control and internal damage remains the dominant failure mechanism. While still not well documented, for internal damage a so called "activation energy" of 0.7 eV may be useful for high temperature accelerated lifetests. Most of the reliability data deals with threshold current increase, however, shifts in far-field pattern and changes in laser modulation characteristics, such as self-sustained oscillations, may affect laser performance in real systems.
IEEE Journal of Quantum Electronics 03/1980; · 1.88 Impact Factor
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IEEE Transactions on Electron Devices 12/1979; 26(11):1843- 1843. · 2.32 Impact Factor
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ABSTRACT: Experimental results are presented for the incidence statistics and physical characteristics of self‐sustained oscillations in the output of (AlGa)As oxide‐defined stripe lasers. Oscillations near threshold are found to be associated with aging but not necessarily to output degradation. The morphology, frequency relationship with current and time resolved near‐field characteristics are presented. These observations are consistent with a rate equation model incorporating saturable absorption. Implications of this model to laser stability are discussed.
Journal of Applied Physics 12/1979; · 2.17 Impact Factor
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ABSTRACT: A novel planar InGaAsP/InP avalanche photodiode structure prepared by vapour-phase epitaxy is described. Avalanche gain up to 20 at 1.3 ¿m and at reverse breakdown of 65 V has been measured.
Electronics Letters 02/1979; · 0.96 Impact Factor
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ABSTRACT: In (AlGa)As, the first of three alloy systems studied, Continuous Wave (CW) operation was obtained at room temperature at a wavelength as low as 7260 A. Reliability in this system was studied in the incoherent mode. Zinc doped devices had significant degradation, whereas Ge or Ge plus Zi doped devices had none. The Al2O3 facet coatings were shown to significantly reduce facet deterioration in all types of lasers, longer wavelength units of that type having accumulated (at the time of writing) 22,000 hours with little if any degradation. A CL study of thin (AlGa)As layers revealed micro fluctuation in composition. A macro-scale fluctuation was observed by electroreflectance. An experimental and theoretical study of the effect of stripe width on the threshold current was carried out. Emission below 7000 A was obtained in VPE grown Ga(AsP) (In,Ga)P with CW operation at 10 C. Lasers and LED's were made by LPE in (InGa) (AsP). Laser thresholds of 5 kA/cm2 were obtained, while LED efficiences were on the order of 2%. Incoherent life test over 6000 hours showed no degradation.
11/1978;
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ABSTRACT: This paper describes in detail the properties of vapor‐grown double‐heterojunction lasers of Ga(As,P)/(In,Ga)P with room‐temperature threshold current densities as low as 3400 A/cm<sup>2</sup> at 7000 Å and 6600 A/cm<sup>2</sup> at 6800 Å. These thresholds are three to eight times smaller than those of (Al,Ga)As lasers in this wavelength range due to the shorter‐wavelength direct‐indirect transition in Ga(As,P). The optical and electrical characteristics of the Ga(As,P)/(In,Ga)P lasers are found to be similar to those of (Al,Ga)As, with fundamental transverse‐mode operation to 70 °C, and spontaneous carrier lifetimes between 5 and 8 nsec typically observed at low current densities.
Journal of Applied Physics 07/1978; · 2.17 Impact Factor
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ABSTRACT: The paper describes in detail the properties of vapor-grown double-heterojunction lasers of Ga(As,P)/(In,Ga)P with room-temperature threshold current densities as low as 3400 A/sq cm at 7000 A and 6600 A/sq cm at 6800 A. These thresholds are three to eight times smaller than those of (Al,Ga)As lasers in this wavelength range due to the shorter-wavelength direct-indirect transition in Ga(As,P). The optical and electrical characteristics of the Ga(As,P)/(In,Ga)P lasers are found to be similar to those of (Al,Ga)As, with fundamental transverse-mode operation to 70 C, and spontaneous carrier lifetimes between 5 and 8 nsec typically observed at low current densities.
07/1978;
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ABSTRACT: A laser diode can simultaneously function as a light source and detector of its own radiation. The addition of a reflecting surface external to the laser produces changes in the laser output power, the current at constant voltage, and the voltage drop across the laser at constant current. The optical feedback reduces the gain necessary to reach the lasing threshold thus increasing the power output at a given dc current level. In this paper we describe the effects of such feedback on the operating characteristics of cw oxide defined stripe AlGaAs lasers.
Applied Optics 07/1978; 17(14):2233-8. · 1.41 Impact Factor
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ABSTRACT: Double‐heterojunction Al 0.3 Ga 0.7 As/Al 0.08 Ga 0.92 As lasers (oxide‐striped and Al 2 O 3 facet coated) were subjected to step‐temperature aging from 60 to 100 °C. The change in threshold current and spontaneous output was monitored at 22 °C. The average time required for a 20% pulsed threshold current increases from about 500 h, when operating at 100 °C, to about 5000 h at 70 °C. At 22 °C, the extrapolated time is about 10<sup>6</sup> h. The time needed for a 50% spontaneous emission reduction is of the same order of magnitude. The resulting ’’activation energies’’ are ∼0.95 eV for laser degradation and ∼1.1 eV for the spontaneous output decrease.
Applied Physics Letters 04/1978; · 3.84 Impact Factor
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ABSTRACT: Double-heterojunction A2(0.3)Ga(0.7)As/Al(0.08)Ga(0.92)As lasers (oxide-striped and Al2O3 facet coated) were subjected to step-temperature aging from 60 to 100 C. The change in threshold current and spontaneous output was monitored at 22 C. The average time required for a 20% pulsed threshold current increase ranges from about 500 h, when operating at 100 C, to about 5000 h at a 70 C ambience. At 22 C, the extrapolated time is about 1 million h. The time needed for a 50% spontaneous emission reduction is of the same order of magnitude. The resulting activation energies are approximately 0.95 eV for laser degradation and approximately 1.1 eV for the spontaneous output decrease
04/1978;
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ABSTRACT: Real-time lifetest data are given for a group of c.w. laser diodes operated continuously for periods as long as 4 years. Out of 24 lasers studied, four lasers have failed to date. This failure rate is compared with accelerated lifetests at 70°C; an estimated m.t.t.f. of ¿ 105 hours at room temperature is obtained.
Electronics Letters 02/1978; · 0.96 Impact Factor
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ABSTRACT: Degradation in short-wavelength (AlGa)As lasers is investigated through lifetests of such devices operated in the incoherent mode. It is shown that degradation increases with emission energy for diodes containing zinc in the p-type (AlGa)As bounding region, whereas diodes containing Ge in this region, although not satisfactory as c.w. lasers because of high resistivity, show no degradation. A way out of this difficulty is proposed through double doping with Ge and Zn, in which case degradation appears to be brought down to the Ge level.
Electronics Letters 02/1978; · 0.96 Impact Factor
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ABSTRACT: This paper reviews theoretical double-heterojunction laser design curves relating the structure with the transverse mode order able to propagate, the degree of radiation confinement to the active region, the maximum field intensity within the device, and the radiated beam shape. The curves presented are general and applicable to any double-heterojunction structure where the spacing of the heterojunctions and the refractive index in the relevant regions are known.
01/1978;
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ABSTRACT: The effect of various diode geometries on the degradation rate of heterojunction diodes with either GaAs or (AlGa)As in the
recombination region has been studied. It is shown that GaAs diodes are particularly sensitive to edge-related degradation
which varies with the current density J as J3/2. The addition of Al to the recombination region considerably reduces the degradation rate of diodes both with and without
exposed edges, and data are reported for Al0.1Ga0.9As stripe-contact edge-emitting structures operating for over 20,000 hours with no change in output at 1000 A/cm2.
Journal of Electronic Materials 08/1977; 6(5):467-481. · 1.47 Impact Factor
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ABSTRACT: There were two main approaches taken to develop shorter wavelength lasers. (1) Based on (AlGa)As and liquid-phase epitaxy, significant new results were obtained: Properties of these laser diodes (power output, spectra, and beam patterns), materials considerations, laser theory, and growth problems are discussed. The design of (AlGa)As layers is discussed from the vertical point of view, and various design curves are given. Horizontal structural requirements are also discussed. Experimental results from measurements done as a function of hydrostatic pressure are correlated with other results. (2) The first heterojunction laser structures using GaAs sub l-x P sub x and In sub y Ga sub l-y P at compositions, where the lattice constants are matched, were grown using vapor-phase growth technology and are described in detail, including experimental device results. Threshold current densities from 3,000 to 5,000 A per sq cm. and emission wavelengths from 6,520 A to 6,640 A were obtained at 77 K. The limiting factor in these devices is nonradiative recombination at the heterojunctions. Life tests on facet-coated (AlGa)As CW diodes are reported.
05/1977;
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ABSTRACT: Contact formed on p-type surface of semiconductor laser has several advantages: highly conductive degenerate region and narrow band gap provides surface for good metal-to-semiconductor contact; lattice parameter of GaAs is 5.6533 A; improved lattice match eases interface strain which reduces interface cracking of semiconductor material.
04/1977;
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ABSTRACT: The paper reports the first low-threshold red-light-emitting heterojunction laser diodes consisting of lattice-matched Ga(As,P)/(In,Ga)P heteroepitaxial layers. A room-temperature threshold current of 3400 A/sq cm was obtained at a wavelength of about 7000 A; this value is substantially lower than those achieved at this wavelength with (Al,Ga)As lasers. For the first time, continuous-wave laser operation at temperatures as high as 10 C has been obtained for GaAs(1-x)P(x).
04/1977;
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ABSTRACT: Vapor‐grown heteroepitaxial structures of GaAs 0.7 P 0.3 /In 0.34 Ga 0.66 P have been fabricated into double‐heterojunction laser diodes with room‐temperature threshold current densities as low as 3400 A/cm<sup>2</sup> at λ L ≃7000 Å. This value is about three times less than the best reported for (Al,Ga)As lasers at this wavelength. From the (Ga,As)P/(In,Ga)P lattice‐matched structures, cw operation at 10 °C has been achieved.
Applied Physics Letters 04/1977; · 3.84 Impact Factor
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ABSTRACT: Long-term operating-life data are reported for (AlGa)As CW laser diodes. The use of half-wave Al2O3 facet coatings is shown to eliminate facet erosion, allowing stable diode operation at constant current for periods in excess of 10,000 h.
02/1977;
