Wyniki wyszukiwania - Biblioteka Nauki

1

InP nanowires quality control using SEM and Raman spectroscopy

100%

Grodecki K. , Dumiszewska E. , Romaniec M. , Strupinski W.

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tom Vol. 34, No. 4

851--855

EN

Three different types of samples of InP nanowires, i.e. undoped, doped with Si and doped with Te, were grown and measured using SEM and Raman spectroscopy. Scanning Electron Microscope (SEM) images showed differences in the length, homogeneity and curvature of the nanowires. The most homogenous wires, grown most perpendicular to the surface, were those Si doped. They were also the shortest. Raman spectroscopy showed that the nanowires doped with Si had the lowest Full Width at Half Maximum (FWHM) TO band, which suggests the highest crystal quality of these wires. For the wires doped with Te, which were the most inhomogeneous, a low energy acoustic band was also observed, which suggests the lowest crystal quality of these structures.

2

High peak power 16 μm InP-related quantum cascade laser

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Szerling A. , Slivken S. , Razeghi M.

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2017

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tom Vol. 25, No. 3

205--208

EN

In this paper ∼16 μm-emitting multimode InP-related quantum cascade lasers are presented with the maximum operating temperature 373 K, peak and average optical power equal to 720 mW and 4.8 mW at 303 K, respectively, and the characteristic temperature (T0) 272 K. Two types of the lasers were fabricated and characterized: the lasers with a SiO2 layer left untouched in the area of the metal-free window on top of the ridge, and the lasers with the SiO2 layer removed from the metal-free window area. Dual-wavelength operation was obtained, at λ ∼ 15.6 μm (641 cm−1) and at λ ∼ 16.6 μm (602 cm−1) for lasers with SiO2 removed, while within the emission spectrum of the lasers with SiO2 left untouched only the former lasing peak was present. The parameters of these devices like threshold current, optical power and emission wavelength are compared. Lasers without the SiO2 layer showed ∼15% lower threshold current than these ones with the SiO2 layer. The optical powers for lasers without SiO2 layer were almost twice higher than for the lasers with the SiO2 layer on the top of the ridge.

3

Badanie centrów defektowych w kryształach półizolującego InP metodą niestacjonarnej spektroskopii fotoprądowej z zastosowaniem odwrotnej transformaty Laplace'a

89%

Pawłowski M. , Kozłowski R. , Kamiński P. , Wierzbowski M. , Jankowski S.

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tom Vol. 46, nr 2-3

41-42

PL

Metoda niestacjonarnej spektroskopii fotoprądowej z zastosowaniem analizy niestacjonarnych przebiegów fotoprądu, opartej na odwrotnej transformacie Laplace'a, została zastosowana do badania struktury defektowej domieszkowanych atomami Fe i niedomieszkowanych półizolujących kryształów InP.

EN

Photoinduced transient Laplace spectroscopy has been applied to study defect centres in Fe-doped and undoped sem-insulating InP. The parameters of defect centres have been extracted from experimental data using a neural network approximation.

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Azotek krzemu stosowany w technologii planarnych fotodiod wykonanych na bazie InP

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Zynek J. , Hejduk K. , Klima K. , Możdżonek M. , Stonert A. , Turos A. , Rzodkiewicz W.

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tom T. 36, nr 4

95-113

PL

Przeprowadzono badania warstw azotku krzemu osadzonych na płytkach z fosforku indu metodą PECVD (Plasma Enhanced Chemical Yapor Deposition) z wykorzystaniem do wytwarzania plazmy dwóch generatorów pracujących na różnych częstotliwościach. Celem badań było ustalenie warunków wytwarzania warstw azotku krzemu stosowanych w technologii planarnych fotodiod wykonanych na bazie InP, w których obszarem absorpcyjnym są studnie kwantowe z InxGa1-xAs. Warstwy azotku krzemu były osadzane w temperaturach pomiędzy 250°C i 300°C. Podstawą do oceny wytworzonych warstw były wyniki badań: ich składu chemicznego, struktury, współczynnika załamania, poziomu naprężeń, rezystywności, wytrzymałości dielektrycznej, stałej dielektrycznej i efektywnej gęstości powierzchniowej ładunków elektrycznych. Stwierdzono, że warstwy osadzane w temperaturze 250°C mają najlepszą strukturę, dobrze spełniają rolę maski w procesie selektywnej dyfuzji cynku, a właściwości elektryczne umożliwiają wykorzystanie ich do pasywacji powierzchni bocznych złącz p-n, pod warunkiem zastosowania odpowiedniego cyklu wygrzewań po procesie osadzania.

EN

Silicon nitride films, deposited on InP wafers by the PECVD (Plasma Enhanced Chemical Vapor Deposition) method, have been investigated in terms of their applicability in the technology of InP based planar photodiodes with the InxGa1-xAs quantum well absorption region. In order to compensate the mechanical stress in the films, the plasma was excited by two radio-frequency sources operating at frequencies of 13,56 MHz and 100 kHz. The films were deposited at different temperatures in the range of 250 - 300°C. The chemical composition of all examined films, determined by the RBS (Rutherford Backscattering Spectrometry) method, is very close to that of stoichiometric Si3N4. The films contain a large amount of hydrogen. The hydrogen content, evaluated by the NRA (Nuclear Reactions Analysis) technique, exceeds 30 %. The silicon nitride films deposited at 300°C have grown much faster on InP wafers than on Si wafers placed beside these and the structure of both films is different. As the films deposited on Si are amorphous with smooth surfaces, the films deposited on InP are heterogeneous with rough surfaces. These last ones exhibit lower Si-N bond concentration, lower refractive index, higher extinction coefficient, lower resistivity and lower dielectric breakdown strength than the films deposited on silicon. Deterioration of the film quality is caused probably by the reaction of phosphorus, released from the InP substrate at the beginning of the deposition process, with deposited SiNx:H. Such films should not be used in the fabrication of InP based planar photodiodes. When the deposition temperature decreases, the properties of silicon nitride films improve. Their structure becomes more homogeneous and the Si-N bond concentration increases. The silicon nitride films deposited on InP at 250°C have the same amorphous structure and the same Si-N bond concentration, determined from FTIR (Fourier Transform Infrared Spectroscopy) absorption characteristics, as the films deposited on silicon. They exhibit the highest refractive index, the lowest extinction coefficient, the highest resistivity and the highest dielectric breakdown strength. These films are continuous, they do not crack during thermal processes and they can be applied as masking layers for the selective Zn diffusion used to form the p-n junctions. Unfortunately the films deposited at 250°C have the highest hydrogen content and the highest effective charge density. These films cannot be applied directly to passivate the p-n junction side surfaces. Measurements of hydrogen depth profiles and of FTIR absorption characteristics have revealed that the amount of hydrogen and of Si-N, Si-H and N-H bonds changed during annealing. An analysis of C-V characteristics of Al/Si3N4:H/InP MIS capacitors containing these films has shown, that annealing of the Si3N4:H films reduced the electronic defect state density at the Si3N4:H/InP interface. It is possible to take advantage of the thermal instability of silicon nitrides deposited by the PECVD method and to reduce the trap state density and the effective charge density by proper annealing processes. These investigations have enabled us to achieve reverse current values as low as 4 - 15 pA at the voltage of - 5 V and 200 - 500 pA at the voltage of -50 V for planar InP diodes with the 320 um diameter p-n junction. A high yield of 90 % is obtained. These results make a good base for development of planar photodiodes with InxGa1-xAs quantum wells inserted into the depletion region of the InP p-n junction.

5

Analiza falowodów ze związków InGaAs, InAlAs i InP dla laserów kaskadowych emitujących w zakresie średniej podczerwieni

89%

Pruszyńska-Karbownik E. , Gutowski P. , Karbownik P. , Sankowska I. , Bugajski M.

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tom Vol. 57, nr 9

23--27

PL

W pracy przedstawiono wyniki obliczeń numerycznych falowodów laserów kaskadowych emitujących promieniowanie o długości fali ok. 5 μm. Rozważano niesymetryczne falowody zawierające podłoże z InP oraz warstwy InGaAs i InAlAs dopasowane sieciowo do InP projektowane do wytworzenia poprzez wzrost epitaksjalny przy wykorzystaniu wyłącznie epitaksji z wiązek molekularnych (MBE). Wyznaczono teoretyczne wartości współczynnika przekrycia pola elektrycznego i obszaru czynnego oraz strat modów poprzecznych dla różnych grubości poszczególnych warstw falowodowych oraz ilości periodów obszaru czynnego. Uzyskane wyniki obliczeń zostały zweryfikowane dla jednej z rozważanych konstrukcji falowodu poprzez porównanie wyznaczonego teoretycznego rozkładu promieniowania w polu dalekim z rozkładem wyznaczonym eksperymentalnie przy użyciu szerokokątnego profilometru goniometrycznego. Względna różnica pomiędzy szerokościami połówkowymi rozkładów teoretycznego i doświadczalnego wyniosła 3,5%.

EN

In this paper, we present results of numerical calculations of quantum cascade laser waveguides emitting radiation with a wavelength of approx. 5 μm. Asymmetric waveguides containing InP substrate and InGaAs and InAlAs lattice matched to InP have been considered. The waveguides have been designed to be manufactured by using molecular beam epitaxy (MBE). We have determined theoretical values of confinement factor and loss of transverse modes for different thicknesses of each waveguide layer. The results of calculations have been verified for one waveguide design by comparing calculated far-field distribution with experimental distribution measured by using a wide-angle goniometric profiler. The relative difference between full width at half maximum of both distributions is 3,5%.

6

Development of the hybrid distributed Bragg reflectors for mid-infrared applications

75%

Mikulicz M. , Badura M. , Rygała M. , Smołka T. , Macherzyński W. , Łozińska A. , Motyka M.

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tom Vol. 32, No. 1

art. no. e149168

EN

In this study, an analysis of the optical performance of two types of distributed Bragg reflector structures based on GaAs and InP material systems was carried out. The structures were designed for maximum performance at 4 μm with their reflectivity achieving between 80 and 90% with eight pairs of constituent layers. To further enhance the performance of these structures, additional Au layers were added at the bottom of the structure with Ti precoating applied to improve the adhesivity of the Au to the semiconductor substrate. The optimal range of Ti layer thickness resulting in the improvement of the maximum reflectivity was determined to be in between 5 and 15 nm.