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Julkaisu: Suomen Lajitietokeskus 2022: Lajiluettelo 2021. Suomen Lajitietokeskus, Luonnontieteellinen keskusmuseo, Helsingin yliopisto, Helsinki. Helttasienet, tatit ja kupusienet ovat kantasienten (Basidiomycota) muotoryhmiä, joihin kuuluvat lähes kaikki muut suursienetpaitsi kääväkkäät. Muotoryhmien lajit eivät välttämättä ole läheistä sukua toisilleen, vaan ne on sijoitettu muotoryhmiin itiöemien ulkoisen samankaltaisuuden vuoksi.Lajiluettelon perustana on vuoden 2010 ja 2019 uhanalaisuuden arviointiin koottu lajilista Suomen helttasienistä, tateista ja kupusienistä (von Bonsdorff ym. 2010, 2019a, 2019b). Suomen helttasienten ja tattien ekologinen luettelo (Kytövuori ym. 2005) on ollut v. 2010 kootun lajiluettelon merkittävänä lähteenä. Luetteloa päivitettiin v. 2019uhanalaisuusarvioinnin yhteydessä ja sen jälkeen muutoksia on tehty v. 2020–2021. Muutoksia on tehty pääasiassa suku-ja lajitasolla sekä virheitä on korjattu. Kaikki edelliseen luetteloon 2020 tehdyt muutokset ovat yksityiskohtaisesti nähtävissä muutostaulukosta (liite 2). Lajikäsitykset muuttuvat nopeaan tahtiin, uusia lajeja löydetään ja kuvataan tieteelle. Sukuja sekä heimoja jaetaan yhä pienempiin ryhmiin. Suomesta on löydettävissä vielä runsaasti uusia kantasienilajeja. Lajiluettelon päivittäminen on siten jatkuvaa. Tieteellinen nimistö koostuu uusimpien taksonomisten julkaisujen, Index Fungorum -tietokannan ja osin vielä Funga Nordican (Knudsen ym. 2012, Index Fungorum Partnership 2021) käyttämästä nimistöstä. Nimistö ei ole täysin vakiintunutta, jonka vuoksi tässä listassa saattaa esiintyä nimiä, jotka poikkeavat muualla käytetyistä. Suomenkieliset nimet on hyväksynyt Suomen Sieniseura ry:n yhteydessä toimiva nimistötoimikunta.Suomalaisia helttasieni-, tatti-ja kupusienilajeja (& ml. kuppimaiset) on luetteloitu yhteensä 2235 lajia.

Two genera: Marchandiomyces, Rectipilus and 16 species of agaricoid and gastroid fungi (Basidiomycota): Clitopilus daamsii, Coprinopsis canoceps, Coprinopsis laanii, Cortinarius albolens, Cortinarius flexibilifolius, Cortinarius megacystidiosus, Cortinarius russulaespermus, Cortinarius tillamookensis, Inocybe assimilata, Laccaria chibinensis, Laccaria violaceibasis, Lactarius porninsis, Lycoperdon mammiforme, Marchandiomyces aurantiacus, Psathyrella pygmaea and Rectipilus fasciculatus are reported here as new to Finland. One genus of ascomycetoid fungi (Ascomycota): Balsamia and four species: Balsamia platyspora, Barbatosphaeria arboricola, Calycellina betulina and Geoglossum elongatum are reported here as new to Finland. A new combination for Belonium betulinum (under Calycellina betulina) is proposed. Information of species recently published elsewhere: Cortinarius alboamarescens, Cortinarius ochroamarus, Cortinarius pastoralis, Cortinarius fulvescentoideus, Cortinarius nymphatus, Cortinarius pseudobulliardioides, Cortinarius tenuifulvescens, Inocybe caprimulgi, Inocybe lacunarum, Inocybe substellata and Lamelloclavaria petersenii is brought here together. New records of little collected and rare taxa: Bovista tomentosa, Geastrum floriforme, Hygrophorus exiguus, Hysterangium crassum, Lactarius serifluus, Lepiota pseudolilacea, Leucopaxillus tricolor, Sarcosphaera coronaria, Scleroderma verrucosum, Squamanita contortipes, Tulostoma niveum and Volvariella reidii are also listed. Corrections of previous information are given on: Hysterangium coriaceum (under Hysterangium crassum) and Lepiota clypeolarioides (under Lepiota pseudolilacea). peerReviewed

Plastic optical fibres, which have a local attenuation minimum at 650 nm, have attracted much interest for low-cost short-haul communication systems. Red vertical-cavity surface-emitting lasers (VCSELs) provide a potential solution as light sources for these systems. The operation of vertical cavity emitters is based on a Fabry–Perot microcavity, which is formed by placing an optically active region inside of two parallel mirrors. These mirrors are usually formed epitaxially. So far, metal organic chemical vapour deposition (MOCVD) has been the major technology used for growing visible VCSELs. Recently, an alternative growth method—solid-source molecular beam epitaxy (SSMBE)—has been introduced to be a viable solution to the fabrication of these structures. The authors present the first MBE-grown visible AlGaInP vertical-cavity surface-emitting lasers. A laser with a 10 μm emitting window has an external quantum efficiency of 6.65% under continuous wave operation and it is still lasing at 45°C. Furthermore, a threshold current less than 1.0 mA is obtained for a device, which has an 8 μm emitting window.

Monolithic top emitting resonant cavity light-emitting diodes (RC-LEDs) operating at 660 and 880 nm have been prepared using solid-source molecular beam epitaxy (SSMBE) growth. Transfer matrix based modelling together with a self- consistent model have been used to optimise the devices' performances. Intermediate-composition barrier-reduction layers were introduced in the distributed Bragg reflector (DBR) mirrors for improving the I-V characteristics and the cavity and mirrors were detuned aiming at maximum extraction efficiency. The fabricated devices showed line widths below 15 nm, CW light power output of 8 and 22.5 mW, and wall-plug efficiencies of 3% and 14.1% in the 660 nm and 880 nm ranges, respectively, while the simulations indicate significant performance improvement possibilities. © 2000 Elsevier Science B.V. All rights reserved.

Monolithic resonant cavity light emitting diodes (RCLED's) for room temperature operation at 650–670 nm and 850–880 nm wavelengths and double-junction GaInP/GaAs solar cells have been designed and grown using a toxic-gas-free solid-source molecular beam epitaxy method. The presence of the microcavity in RCLED's causes strong cavity enhancement, which can be utilized to modify natural spontaneous emission. These devices are shown to exhibit performance characteristics that are better than those of conventional LED's in many ways. They may be suitable for optical fibre communications and interconnects where a relatively high speed, good fibre coupling efficiency, nearly monochromatic spectrum, and long-term reliability are desirable. The GaInP/GaAs cascade cells also reported in this paper are state-of-the-art, exhibiting conversion efficiencies up to 23.2% at one-sun air-mass-zero illumination. With so high efficiency and good radiation resistance, the cascade solar cells are potential candidates for solar power generation of satellites.

Time resolved photoluminescence and deep level transient spectroscopy have been used to monitor the effect of rapid thermal annealing on bulk GaInP and GaInP/AlGaInP quantum wells grown by solid source molecular beam epitaxy similar to those used in 650 nm range lasers. Following rapid thermal annealing at temperatures up to 875 °C, reductions in the concentration of several deep level traps are observed. Correlation of these data with photoluminescent intensity and lifetime measurements indicate that the defect labeled N3, 0.83 eV below the conduction band, is the dominant recombination center. The combination of these two transient spectroscopy measurement techniques is therefore not only able to measure the change in deep level concentration, but also to correlate this change with improved carrier lifetimes and, ultimately, reduced threshold current densities in quantum well lasers. There is also evidence to suggest that this same defect, possibly a phosphorous vacancy or a related complex, plays an im...

AlxGayIn1−x−yAs/InP strained-layer multiple-quantum-well lasers emitting at 1.3 µm have been grown by solid source molecular beam epitaxy, and the performance characteristics have been studied. The lasers contain 4, 5, or 6 compressively strained quantum wells in the active region. They exhibit low transparency current densities, high gain coefficients, and high characteristic temperatures compared to conventional GaInAsP/InP quantum well lasers. The results show that desired lasing features can be achieved with relatively simple layer structures if the doping profiles and waveguide structures are properly designed and the material is grown to high structural perfection.

We report on the solid source molecular beam epitaxy growth (SSMBE) of resonant cavity light-emitting diodes (RCLED) operating at 660 and 1300 nm wavelengths using valved cracking cells. The 1300 nm RCLED reported here is according to the best of the author's knowledge the first monolithic RCLED made on that wavelength. The performance characteristics of the grown devices show that SSMBE is a viable growth method for complex vertical cavity structures.

We have studied the growth of 600-nm range strained GaInP/AlGaInP quantum well lasers using solid phosphorous in a valved cracking cell by molecular beam epitaxy. Closely optimized growth conditions for AlGaInP-based materials have been determined. As a result, high-power red laser diodes have been prepared. Output power levels up to 3 W for the 670 nm, 2 W for the 650 nm and 1 W for the 630-nm lasers have been achieved in continuous wave mode. Preliminary life-tests have also been carried out for 670 and 650 nm devices.

We have prepared high-power 600 nm spectral band quantum well lasers using all-solid-source molecular beam epitaxy for layer growth. An output power up to 3 W in continuous wave mode has been demonstrated at the nominal wavelength of 670 nm, 2 W at 650 nm and 1 W at 630 nm. The threshold current densities are 350- for nm, 500- for nm and less than for nm. The characteristic temperature of threshold current falls within the range of K at nm and is about 60 K at nm. The slope efficiency is between 0.50 and 0.58 W per facet for uncoated devices of 1 mm in cavity length. Maximum observed wall-plug efficiencies are between 30 and 48% for mirror coated lasers. Preliminary lifetests have been carried out for the 650 and 670 nm lasers suggesting that these lasers will be quite reliable in operation.

The laser diode structures reported up to now in literature for the red wavelength range are still far from optimal – mostly because many of the desired characteristics are contradictory coupled. Some of the contradictory coupled laser diode characteristics are investigated and a novel transverse layer structure is proposed. Both optical simulation and a fully self-consistent model are used in a design optimization methodology and simple evaluation and optimization criteria are derived. A number of the analyzed high-power edge-emitting GazIn1−zP/(AlxGa1−x)yIn1−yP/GaAs quantum well laser structures were prepared using all-solid-source molecular beam epitaxy for layer growth and remarkable performances were obtained (continuous wave output powers of 3 W at 670 nm, 2 W at 650 nm, and 1 W at 630 nm; threshold current densities of 350–450 A/cm2 for 670 nm, 500–540 A/cm2 for 650 nm, and less than 700 A/cm2 for 630 nm). The good agreement between measurements and simulations for the prepared structures indicate that significant performance improvements – predicted by the simulations – are still possible. The presented novel structure and design optimisation procedure can also be applied to laser diode structure optimisation in other emission ranges – like, for example, in the case of 800 nm-range edge emitting AlxGa1−xAsyP1−y/GazIn1−zAswP1−w/GaAs laser diodes.

All-solid-source molecular beam epitaxy (SS-MBE) is a novel variant of MBE. It allows for toxic-gas-free growth of III–V compound semiconductors, including phosphides. We have examined the quality of SS-MBE-grown phosphorus containing heterostructures and laser diodes. The results discussed in this article show that state-of-the-art quantum well (QW) materials and lasers, covering a wide range of bandgaps from red to infrared, can be prepared by SS-MBE.

We report on the growth of Ga x In 1-x As γ P 1-γ and (Al x Ga 1-x ) 0.51 In 0.49 P thin films and related laser diode structures by solid-source molecular beam epitaxy, using valved cracking cells as sources of group-V fluxes. As shown here, high-quality materials, including strained-layer quantum well lasers for a large range of wavelengths from 0.68 to 1.69 μm, can be grown in a reproducible way. The performance characteristics of the fabricated lasers are comparable to those obtained by using other growth methods.

High-performance visible compressively strained single quantum well laser diodes have been grown by solid source molecular beam epitaxy. The waveguide region was designed to have a low Al content in order to enhance the optical field confinement and to improve the material quality. The threshold current density for an infinity long cavity length was estimated to be . The highest external quantum efficiency of 37% per facet was obtained for a cavity length of 480 . A characteristic temperature of 130 K was measured in the temperature interval from to .

InGaAs/GaInAsP/GaInP ridge waveguide 980-nm laser diodes for pumping light into erbium doped fiber amplifiers are reviewed. These lasers have very good performance characteristics. They exhibit kink-free, single mode emission up to a power of 250 mW with a slope efficiency of 0.7 to 0.95 W/A, a thermally limited maximum power of 450-500 mW, and the threshold current density of about 150 A/cm/sup 2/. They are relatively stable against temperature variations. A 100 mW power from a fiber-pigtail module has been demonstrated. These lasers withstand severe thermal rollover tests without showing degradation effects. Preliminary lifetime tests indicate that their mean-time-to-failure (MTTF) may be very long, from several hundred thousand to one million hours, if not limited by sudden failure.

Summary Much of the macroecological information about microorganisms is confounded by the lack of standardized methodology, paucity of metadata and sampling effect of a particular substrate or interacting host taxa. This study aims to disentangle the relative effects of biological, geographical and edaphic variables on the distribution of Alnus-associated ectomycorrhizal (ECM) fungi at the global scale by using comparable sampling and analysis methods. Ribosomal DNA sequence analysis revealed 146 taxa of ECM fungi from 22 Alnus species across 96 sites worldwide. Use of spatial and phylogenetic eigenvectors along with environmental variables in model selection indicated that phylogenetic relations among host plants and geographical links explained 43 and 10%, respectively,in ECM fungal community composition, whereas soil calcium concentration positively influenced taxonomic richness. Intrageneric phylogenetic relations among host plants and regional processes largely account for the global biogeographic distribution of Alnus-associated ECM fungi. The biogeography of ECM fungi is consistent with ancient host migration patterns from Eurasia to North America and from southern Europe to northern Europe after the last glacial maximum, indicating codispersal of hosts and their mycobionts.

Multi-quantum well structures exhibiting intraband impact ionization were studied. Fabricated devices consisted of donor doped GaAs or In 0.20 Ga 0.80 As quantum wells and undoped Al x Ga 1− 4tx As barrier regions. Effective gain-per-stage was found to be strongly dependent on structure design and measurement conditions (incident light intensity, chopping frequency and temperature). The limits of the validity of the current single-valley model for these structures are discussed.

Resonant cavity light-emitting diodes (RCLEDs) operating at λ≅660 nm and λ≅880 nm have been fabricated and studied. The RCLED layer structures consisted of 1−λ thick cavities sandwiched between AlGaAs distributed Bragg reflectors. The cavities were detuned to improve temperature stability and light extraction. The temperature induced red-shifts in the peak emission wavelength were found to be 0.14 and 0.22 nm °C−1 for the 660- and 880-nm devices, respectively.

Fiber lasers have made significant progress in terms of power output, beam quality and operational robustness over the past few years. Key to this progress has been advances in two technologies - fiber technology and 9xx nm diode laser pump technology based on single emitters. We present the operational characteristics of our new high brightness 9xx nm fiber laser pump sources based on diode laser bars and diode laser bar arrays and discuss the design trade offs involved for realization of devices focused on this application. These trade offs include achieving the lowest slow axis divergence while maintaining high wall plug efficiency and minimizing facet power density to maximize reliability.

We describe the performance and reliability of high power vertical diode stacks based on silicon monolithic micro-channel coolers (SiMMs) operating at >1000W/cm 2 CW at 808 and 940nm. The monolithi c nature of these stacks makes them inherently robust an d compact. Typical emitting di mensions for a 10-bar stack are ~8.8mm x 10mm with CW output power up to 1.5kW. Originally developed at Lawr ence Livermore National Laboratory and now actively being developed for commercial applications at Coherent, this tech nology offers several advantages over current copper-based micro-channel coolers. These de vices do not require use of DI water, strict monitoring and control of the pH level, careful control of the water velo city, or sealed cooling systems. The need for hydrostatic seal s is also drastically reduced. A typical ten bar stack requires only 2 o -ring seals, compared to 20 such seals for a similar stack using copper micro-channel cooling. Mature and r eadily available wet etching tech nology allows for co st effective batch fabrication of the sub-mount structure while achieving repeatable high precision components based on photolithographic fabrication processes.

In this letter, the authors report a very high quantum efficiency of 91% for antireflection/high-reflection-coated GaInP-AlGaInP ridge waveguide laser diodes operating at 650 nm range. The laser structure was grown by solid-source molecular beam epitaxy. The laser diodes performed stable single-mode operation up to 60 mW. Threshold current as low as 50 mA was measured for 5.5/spl times/600 /spl mu/m/sup 2/ laser diodes. To the authors' best knowledge, this is among the best ever reported efficiency for visible lasers.

Ongoing optimization of epitaxial design within Coherent device engineering has led to a family of high power-conversion-efficiency (PCE) products on conductively cooled packages (CCP) and fiber array packages (FAP). At a 25 °C heat sink temperature, the PCE was measured at 71.5% with 75W CW output power on 30% fill-factor (FF) bars with passive cooling. At heat sink temperatures as high as 60 °C the PCE of these bars is still maintained above 60%. Powered by such high efficiency 9xx nm diodes, Coherent FAP products have consistently exceeded 55% PCE up to 50W power levels, with 62% PCE demonstrated out of the fiber. High linear-power-density (LPD) operation of 100μm x 7-emitter bars at LPD = 80 mW/μm was also demonstrated. Bars with 7-emitter were measured up to 140W QCW power before catastrophic optical mirror damage (COMD) occurred, which corresponds to a COMD value of 200mW/μm or 2D facet power density of 29.4 MW/cm 2 . Leveraging these improvements has enabled high power FAPs with >90W CW from an 800μm-diameter fiber bundle. Extensive reliability testing has already accumulated 400,000 total real-time device hours at a variety of accelerated and non-accelerated operating conditions. A random failure rate 30,000 hours of median lifetime at a 90% confidence level. More optimized 30% FF 9xx nm bars are under development for power outputs up to 80W CW with extrapolated median lifetimes greater than 20,000 hours.

We have examined the influence of rapid thermal annealing on the performance characteristics of GaInP/AlGaInP quantum well lasers which were grown by all-solid-source molecular beam epitaxy. It was found that when the laser structures were annealed the threshold current densities of the lasers decreased significantly. This improvement in lasing performance could be associated with the possibility that annealing removed nonradiative recombination centers from the quantum wells. The emission wavelength, differential quantum efficiency, and characteristic temperature were not affected to any remarkable extent, indicating that the interdiffusion of group-III elements did not damage the structures.

A novel conception of light-emitting diodes, namely resonant-cavity light-emitting diode, has been proved to have several improvements over conventional LED’s including better spectral purity and enhanced output intensity [1]. However, the fabrication process remains comparable to that of a conventional LED. This makes an RCLED a competitive challenger for a vertical-cavity surface-emitting laser (VCSEL) for various applications in local area networking, optical computing measurement systems and densely packed displays.

Al-free diode laser bar arrays emitting at SOS nm, suitable for Nd:YAG pumping are currently subject of intense study because of their believed superiority concerning catastrophic optical damage (COD) and long-term reliability.

High-performance strained-layer GaInAs-GaInAsP-GaInP separate-confinement quantum-well lasers emitting at /spl lambda/=980 nm were grown by all solid-source molecular-beam epitaxy. Valved cracker cells were employed to generate group-V beam fluxes. Fabricated ridge-waveguide lasers exhibited stable, kink-free, single-mode operation up to 260 mW. A maximum output power of 550 mW was achieved. Complete thermal roll-over tests were done tens of times without any sign of degradation for p-side up-mounted lasers. Preliminary lifetime tests for over 4500 h at 150-mW power level indicate that these aluminum-free pump lasers are very reliable sources for pumping light into erbium-doped fiber amplifiers.

We report on the growth of 980‐nm strained‐layer InGaAs/GaInAsP/GaInP separated confinement quantum well lasers using all solid source molecular beam epitaxy. Valved cracker cells were employed for both phosphorus and arsenic. Fabricated lasers exhibited excellent performance that is comparable to similar lasers grown by gas source molecular beam epitaxy in our laboratory. A maximum output power of 450 mW and over 250 mW in single mode operation was achieved for ridge waveguide lasers with AR/HR coated facets.

The first GaInAsP based laser diode grown by all solid source molecular beam epitaxy is reported. A strained-layer GaInAsP/InP separate confinement heterostructure multiquantum well laser emitting at 1.35 mu m was prepared. A low threshold current density of 510 A/cm/sup 2/ was obtained for a broad-area laser having a cavity length of 1300 mu m.

Al/sub x/Ga/sub y/ln/sub 1-x-y/As/InP strained-layer multiple quantum well lasers emitting at 1.3 /spl mu/m have been grown by solid source molecular beam epitaxy, and the performance characteristics have been studied. The lasers contain 4, 5, or 6 compressively strained quantum wells in the active region. They exhibit low transparency current densities, high gain coefficients, and high characteristic temperatures compared to conventional GaInAsP-InP quantum well lasers. The results show that desired lasing features can be achieved with relatively simple layer structures if the doping profiles and waveguide structures are properly designed and the material is grown to high structural perfection.

In this paper, we have studied InAsP/InGaP/InP strain-compensated lasers with 10 QWs grown by all solid source molecular beam epitaxy (SSMBE). High characteristic temperature T/sub 0/ value of about 100 K in the temperature range 20-80/spl deg/C and low threshold current density of 87 A/cm/sup 2/ per well for infinite cavity length are reported. Our results clearly demonstrate the suitability of the InAsP/InGaP strain-compensated system for lasers operating at elevated temperatures. Also, together with our earlier studies the obtained results show that SSMBE is a competitive growth method for optoelectronic devices.

All-solid source molecular beam epitaxy, SS-MBE, has opened the possibility of growing GaInAsP and AlGaInP semiconductors over a wide band-gap range without use of toxic gases as source materials. In particular, the key discovery facilitating a controlled alloying of phosphorus with other elements has been the development of multi-zone P/sub 2/ cells. With these cells one can couple ease of solid material handling with a long source material lifetime and convenient flux control previously only available with gaseous sources. In this paper, we concentrate on phosphorus containing lasers and super-bright resonant-cavity light emitting diodes (RC-LEDs), grown by SS-MBE on InP or GaAs substrates. The lasers discussed cover a spectral region from 630 nm to 1300 nm; the RC-LED's emit at 670 nm and 1300 nm. Their performance characteristics, including reliability data, will be presented.

All solid source molecular beam epitaxy (SSMBE), where only solid group-V sources are used, eliminates fabrication problems. We present our results on the development of 1.3 /spl mu/m AlGaInAs-AlInAs-InP laser diodes, and show that high-performance laser diodes can be prepared from SSMBE grown material.

We report on 808 nm wavelength lasers grown by solid source molecular beam epitaxy. These tensile strained GaInP-GaInAsP single quantum well lasers exhibited a low threshold current density of 230 A/cm/sup 2/ with a cavity length of 2 mm. A 1 mm long device launched 2 W CW output power with a wallplug efficiency of nearly 50%. The measured lasing characteristics compare favorably to those of 808 nm lasers grown by other growth techniques.

AlGaInP based red-emitting laser diodes have become increasingly attractive as light sources in various applications. Until now metalorganic chemical vapor deposition (MOCVD) has been the prevailing growth technique for producing GaInP/AlGaInP quantum well laser diodes with low threshold currents and high optical output power. An alternative growth method for AIGaInP alloy is solid source molecular beam epitaxy (SSMBE), where phosphorus flux is supplied by a valved cracking cell loaded with elemental red Phosphorus. However, the performance of SSMBE grown red laser diodes has typically been clearly inferior to that attained by MOCVD. In this paper we present our results on development of 670 nm laser diodes and show that high-performance laser diodes can be prepared from SSMBE grown material.

We have studied the growth of (Al/sub x/Ga/sub 1-x/)/sub 0.51/In/sub 0.49/P quaternary alloy and GaInP/AlGaInP heterostructures using solid, elemental phosphorus in a valved cracking cell by molecular beam epitaxy. The results obtained have been applied for the growth of strained-layer quantum well laser structures emitting in the red-light region. In order to further assess the quality of our materials, the grown laser structures have been processed into laser diodes that have been characterized. The measured threshold current densities of the 1 mm long as-cleaved broad-area laser diodes were 385 A/cm/sup 2/ and 820 A/cm/sup 2/ at 680 nm and 633 nm, respectively. To the best of our knowledge these values are the lowest reported threshold current densities for SSMBE grown lasers in this wavelength range. A high T/sub 0/ of 113 K was obtained for double-QW in the temperature interval of 20/spl deg/C-90/spl deg/C. All these results clearly demonstrate that state-of-the-art 600-nm-range laser diodes can be prepared using only solid sources.

Unipolar electron impact ionization and multiplication in photodiodes consisting of GaAs/AlGaAs multiquantum well heterostructures have been observed. In these diodes, electrons generated by photon absorption and accelerated in the barrier regions scatter bound electrons from the donor‐doped GaAs wells. Gain‐per‐well of 1.13±0.05 and total gain of 100 for the multiplication region have been demonstrated. The photodiodes exhibit high dark current which arises from thermionic emission and tunneling of electrons out of the wells.

A GaAs/AIGaAs staircase SAM-APD containing a 10 stage undoped staircase multiplication region is demonstrated. Doping dipoles were inserted in GaAs/Al0.45Ga0.55As interfaces to increase the effective conduction band offset. Typical dark current at 0.9VB was 70pA. The maximum avalanche gain of 1500 was measured near the onset of breakdown. An effective ionisation rate ratio kaff = 0.2 was obtained from multiplication noise measurements.

The effect of oxygen incorporation on electrical and optical properties of Be-And Si-doped InP grown by solid source molecular beam epitaxy has been studied. Oxygen was observed to reduce both the Be and Si doping efficiencies in InP and to introduce recombination centers that degrade the photoluminescence property. The compensation in Be-InP was more pronounced than in Si-InP. With high oxygen impurity concentration, Be-InP was found to be n-Type in Hall measurements. Electrical inactivity of Be is likely due to the formation of Be-O complexes in InP. Oxygen was originated from the phosphorous source and could be reduced by employing lowered phosphorous cracker temperature.

Monolithic top-emitting resonant cavity light-emitting diodes (RCLEDs) have been fabricated by solid-source MBE. The RCLEDs in the 650-nm range, with modulation bandwidths exceeding 180 MHz, are possible low-cost transmitter candidates for systems using plastic optical fibers (POFs), such as IEEE-1394 at 100 Mb/s and 200 Mb/s and ATM at 155 Mb/s. Modulation bandwidth of greater than 120 MHz and light power of 2 mW (cw) have been achieved for (phi )84-micrometer devices driven at a 40 mA current. Accelerated aging tests for 27,500 device-hours indicate no degradation in output power. A variation in device temperature significantly modifies the far-field pattern and thus the fiber coupling efficiency, due to a cavity detuning effect. The effects of detuning and the temperature and bias dependencies of the devices are investigated. The 880-nm RCLEDs have a maximum output power of 25 mW. Applications include open-air optical communication systems, collision avoidance and measurement systems.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In the already classical separate confinement (SCH) quantum well (QW) semiconductor laser diode structures many of the desired performances are contradictory coupled through the structural parameters -- i.e. a structural parameter modification leading to the improvement of one or more laser performances will produce the deterioration of at least another performance. Based on an analysis of this contradictory coupling a novel transverse layer structure that alleviates the problem and enables improved laser diode performances is proposed. Both optical simulation and a fully self-consistent model are used in a design optimization methodology and simple evaluation and optimization criteria for the new transverse structure are derived. A number of the analyzed high-power edge-emitting GazIn1-zP/(AlxGa1- x)yIn1-yP/GaAs quantum well laser structures were prepared using all-solid-source molecular beam epitaxy (SS-MBE) for layer growth and remarkable performances were obtained (continuous wave output powers of 3 W at 670 nm, 2 W at 650 nm, and 1 W at 630 nm; threshold current densities of 350 - 450 Angstrom/cm2 for 670 nm, 500 - 540 A/cm2 for 650 nm, and 600 - 680 A/cm2 for 630 nm). Although only a few of the optimization features were implemented the good agreement between measurements and simulations for the prepared structures indicate that significant performance improvements -- predicted by the simulations -- are still possible.

Monolithic top emitting resonant cavity light-emitting diodes operating in the 650 and 880 nm ranges have been prepared using solid-source molecular beam epitaxy growth. Transfer matrix based modeling together with a self- consistent model have been sued to optimize the devices' performances. The design of the layer structure and doping profile was assisted by computer simulations that enabled many device improvements. Among the most significant ones intermediate-composition barrier-reduction layers were introduced in the DBR mirrors for improving the I-V characteristics and the cavity and mirrors were detuned aiming at maximum extraction efficiency. The fabricated devices showed line widths below 15 nm, CW light power output of 8 and 22.5 mW, and external quantum efficiencies of 3 percent and 14.1 percent in the 650 nm and 880 nm ranges, respectively - while the simulations indicate significant performance improvement possibilities.

We report on resonant cavity light-emitting diodes, operating at 660, 880, and 1300 nm wavelengths. Some of the characteristic features of these devices will be discussed. The devices were grown by all-solid-source molecular beam epitaxy (SSMBE). The results provide clear-cut evidence that SSMBE is a viable method to growth of phosphorous containing semiconductors.

This paper presents the performance characteristics and reliability data of AlGaInP-based VISIBLE laser diodes emitting at the wavelengths from 630 to 670 nm. The lasers are grown by toxic gas free solid source molecular beam epitaxy.

An alkali metal dispenser was employed as a lithium dopant source in the growth of ZnSe films by molecular beam epitaxy in an attempt to obtain p -type conductivity. Depending on the doping level, these films exhibited either dominant acceptor-bound exciton emission in low-temperature photoluminescent spectra, indicative of p -type conversion, or strong donor-acceptor-pair emission, likely due to transitions between interstitial Li donors and substitutional Li acceptors. Electrical resistivity was very high preventing a direct measurement of the majority carriers.

This paper presents the performance characteristics and reliability data of GaInAsP- and AlGaInP-based laser diodes emitting at the wavelengths from 650 to 1,300 nm. The lasers are grown by toxic-gas-free all-solid-source molecular beam epitaxy (SS-MBE).

Summary form only given. Nearly 1 W cw power at 25 C was obtained from a 50-/spl mu/m broad-area InGaP SQW laser emitter operating at 652 nm. The devices were grown by solid source molecular beam epitaxy (SSMBE) and offer the possibility of a compact source suitable for photodynamic therapy.

High power 600-nm-range AlGaInP-based laser diodes are attractive light sources for various applications, such as photodynamic therapy, optical pumping of tunable solid-state lasers, projection displays, bar-code readers, and high speed printers. The reliability of AlGaInP-based lasers has been a widely debated issue lately. In order to achieve reliable high-power operation of lasers in the red, low-threshold and high efficiency operation should be established. This could be achieved by using strained active regions and by optimizing the growth conditions for the laser material. In addition, proper laser structure design and facet coating procedures are indispensable to increase the maximum usable output power before the catastrophic optical damage takes place.