| 1. |
- Bertone, Daniele, et al.
(författare)
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Etching of InP-based MQW laser structure in a MOCVD reactor by chlorinated compounds
- 1998
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 195:1-4, s. 624-629
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Tidskriftsartikel (refereegranskat)abstract
- Four different chlorinated compounds: 2-chloropropane, dichloromethane, chloroform and carbon tetrachloride have been used to etch InGaAsP/InP MQW laser structures partially masked. Etching experiments were performed in a home-made LP-MOCVD reactor with argon or argon + hydrogen as carrier gas, using phosphine (PH3) or tertiarybutylphosphine (TBP) to prevent thermal decomposition. The etching temperature as well as the chlorinated compound flow were varied to obtain the best trade-off between etch rate and surface morphology. The optimized experimental conditions were applied to etch mesa stripes in a SCH-MQW laser structure, for the first time to our knowledge, followed by lateral InP : Fe regrowth in the same step. Threshold current as low as 4 mA (best value)-6 mA (typical value) and differential quantum efficiency higher than 20% for SI-BM MQW laser have been achieved.
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| 2. |
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| 3. |
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| 4. |
- Campi, Roberta, 1972-
(författare)
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High performance materials and processing technology for uncooled 1.3 μm laser diodes
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis investigates different material systems and processing technology for high temperature compatible laser diodes used in volume applications within the 1.3-μm telecom wavelength window. Laser diodes built from such materials are much desired in order to eleminate the need for active temperature control needed in current systems, which significantly increases both complexity, size and cost. The structures were grown by Metal-Organic Chemical Vapor Deposition (MOCVD) and the evaluation of materials was performed using different characterization methods such as High-Resolution X-Ray Diffraction (HR-XRD), Photoluminescence (PL), Time-Resolved Photoluminescence (TR-PL). Fabrication and evaluation of Fabry-Perot lasers with different geometries was used to check the material quality and temperature performance. A novel in-situ etching technique was developed for the use i future more advanced, buried hetrostructure lasers. The first studied materials system was AlGaInAsP/InGaAsP/InP. To handle a 5-element material with the precision required, modelling of the materials and heterostructure properties was performed. The addition of Al to the InGaAsP barrier allows better electron confinement with little change in valence band properties. The optimum aluminium content was found to be about 12%. Although the effect of Al could be identified, it was not sufficient with T0 of only 90 K only up to 60 °C. A second materials system InGaP/InAsP/ InP initially looked quite promising from a materials and quantum well design point of view but encountered severe problems with the device integration and further work was discontinued. The main effort was therefore was devoted to a third materials system: AlGaInAs/AlGaInAs/InP. This material system is not unknown but has hitherto not found a widespread application for fibre optic applications. In this work, the MOCVD growth of 1.3 μ;m quantum well laser structures was optimized and ridge waveguide laser devices with excellent temperature performance was fabricated (T0 = 97 K at 85 °C). A ridge waveguide laser was identified as suitable structure since it requires only a single epitaxial growth, thus avoiding the main problem of oxidation of Al based buried structures. The dynamic performance was excellent up to 110 °C and the device fabrication is highly reliable (lifetime >7000 h). This high yield uncooled ridge Fabry-Perot laser process has now been transferred to production and is applied in short length 10 Gb/s multimode links. In order to further improve the usefulness of the Al-containing materials in even higher performance devices needed in future applications developments towards fully buried heterostructure device geometry were also pursued. To overcome difficulty of oxidation of Al containing layers at the mesa walls an in-situ etching technique was implemented. Different chemistry approaches were investigated and the first results of lasers devices were reported.
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| 5. |
- Campi, Roberta, et al.
(författare)
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Highly reliable and high-yield 1300-nm InGaAlAs directly modulated ridge fabry-Perot lasers, operating at 10-gb/s, up to 110°C, with constant current swing
- 2006
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 24:1, s. 143-149
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Tidskriftsartikel (refereegranskat)abstract
- Transceivers for 300-m multimode links, based on a serial 10-Gb/s laser source and incorporating a receiver based on electronic dispersion compensation (EDC), are creating the first high-volume application for a 10-Gb Fabry-Perot (FP). A highly reliable and high-yield uncooled ridge FP laser is presented. The device shows excellent power characteristics in the 25 divided by 150 degrees C temperature range with very high To (95 K in the temperature range 0 divided by 85 C and still 78 K at 150 degrees C). Outstanding dynamic performances are also shown: 6 dB of extinction ratio can be achieved up to 110 degrees C by using a constant current swing of 50 mA. Because of their enhanced performances, these devices have enabled single temperature setting of the optical module, leading to a significant test cost reduction.
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| 6. |
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| 7. |
- Campi, Roberta, et al.
(författare)
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MOVPE growth of strained 1300 nm InGaAlAsP/ InGaAsP quantum well structures
- 2000
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Ingår i: 12th International Conference on Indium Phosphide and Related Materials. ; , s. 380-383
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Konferensbidrag (refereegranskat)abstract
- In this work we propose novel 1.3 μm InGaAlAsP/InGaAsP MQW laser structures designed for high-temperature operation. The effects of aluminum on the band offsets and carrier confinement in MQW structures have been investigated. Epitaxial structures exhibited very high photoluminescence (PL) and sharp satellites in high-resolution x-ray diffraction. The carrier transport issues were further investigated using femtosecond time-resolved PL. Broad area lasers exhibited values of threshold current density of 261 A/cm-2 per quantum well and a slope efficiency of 0.25 W/A. The observed T0 values of 69 K for pure InGaAsP barriers increased to about 95 K for an Al content of about 12.5%, in accordance with expectations.
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| 8. |
- Campi, Roberta, et al.
(författare)
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Strain effects on highly strained InAsP/InGaP multi-quantum well structures grown by MOVPE using TBAs and TBP
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 265:3-4, s. 357-366
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the strain on the material quality of highly strained InAsP/InGaP multi-quantum well (MQW) systems has been studied. The main purpose of our study was to investigate and optimise the epitaxial crystal quality of different QWs structures in order to obtain the best well-barrier system. The strain-compensation technique enabled us to grow InAsP/InGaP-MQWs with strain exceeding ±1% and as many as 20 wells without any material deterioration. The strain-compensated structures have been grown by metalorganic vapor phase epitaxy (MOVPE) using TertiaryButylArsine (TBAs) and TertiaryButylPhosphine (TBP) as group V precursors. Photoluminescence (PL), High-Resolution X-ray Diffraction (HR-XRD), Transmission Electron Microscopy (TEM) have been used to study the MQW structures. Net strain, shear strain and residual strain have been used to evaluate the strain effects on the material quality: strain compensation and abruptness of MQW interfaces are needed in order to obtain high performance material. In addition, in this system, the experimental data suggest that the influence of the strain compensation at the interface between well and barrier, which we define as 'symmetrical' strain, seems to be important in determining the quality of the MQW stacks.
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| 9. |
- Campi, Roberta, et al.
(författare)
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Studies on the carrier transport in InGaAlAdP/InGaAsP quantum well structures emitting at 1.3 μm
- 2000
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Ingår i: Conference on Lasers and Electro-Optics Europe - Technical Digest. - 0780363191 ; , s. 141-
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Konferensbidrag (refereegranskat)abstract
- A novel approach to improve high temperature performance in the IngaAsP lasers was examined by adding aluminum to the barrier,which allows to increase conduction band offset. To find optimal heterostructure parameters, different barrier material compositions were examined in structures with InGaAsP compressively strained wells and tensile strained InGaAlAsP barriers. The MQW structures were fabricated by low pressure MOVPE.
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| 10. |
- Codato, Simone, et al.
(författare)
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Ga assisted in situ etching of AlGaInAs and InGaAsP multi quantum well structures using tertiarybutylchloride
- 2005
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 282:1-2, s. 7-17
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we present Studies on the in situ etching (ISE) technique using tertiarybutylchloride (TBCl) as etchant precursor in a metal organic vapour phase epitaxy (MOVPE) reactor. Experiments were made in PH3 and PH3-free environments at low pressures (50-100 mbar) and in a low-temperature regime (545-600 degrees C). In particular, the combination of standard reactive ion etching (RIE) and ISE for the realization of suitable mesa structures for device applications has been systematically investigated. In our etching experiments InP, InGaAsP and Al-containing multi quantum wells (MQWs) have been used as etching targets. Particular efforts were devoted to the etching of Al-containing structures. For this material, the addition of trimethylgallium (TMGa) during the etching resulted to be of key importance in providing good surface morphology and etching of the MQW structure. The role of Ga species in the etching mechanisms will be discussed. The dependence of surface morphology and mesa shape on etching conditions, in particular, temperature, chlorine concentration, gallium concentration and etching time, will be described.
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