Search results

1

Epitaxial Growths of II-VI Compounds on (110) Substrates

100%

Cywiński G., Wojtowicz T., Kopalko K., Karczewski G., Kossut J.

Acta Physica Polonica A

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1998

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vol. 94

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issue 2

281-284

EN

We studied epitaxial growth conditions of II-VI semiconductors on (110) substrates, which is indispensable for fabrication of T-shaped quantum wire structures. We experimented with different types of (110)-oriented substrates and monitored the surface quality of deposited layers in situ by reflection high energy electron diffraction and ex situ by photoluminescence. The aim of this work is to find optimum growth conditions of II-VI compounds on a cleaved edge of a superlattice as required by the overgrowth method.

2

Search for T-Shaped Quantum Wires in CdTe/CdMg(Mn)Te System

100%

Cywiński G., Wojtowicz T., Karczewski G., Kossut J., Gębicki W.

Acta Physica Polonica A

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1998

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vol. 94

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issue 2

277-280

EN

We attempted to produce and to investigate T-shaped wire structures of II-VI compounds. Our samples were grown on GaAs hybrid substrates in a two-stage growth process. The photoluminescence measurements resulted into two different possible polarization behaviors of recorder signal. We interpret one of these behaviors as due to quantum wire formation.

3

Near IR Refractive Index for GaInN Heavily Doped with Silicon

86%

Cywiński G., Kudrawiec R., Rzodkiewicz W., Kryśko M., Litwin-Staszewska E., Misiewicz J., Skierbiszewski C.

Acta Physica Polonica A

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2009

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vol. 116

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issue 5

936-938

EN

The authors report on growth and results of infrared measurements of GaInN heavily doped with silicon. The lattice matched to GaN epitaxial layer of Ga_{0.998}In_{0.002}N:Si has been grown in plasma assisted molecular beam epitaxy in the metal rich conditions. The room temperature Hall concentration and mobility of electrons are 2× 10^{20} cm^{-3} and 67 cm^{2}/(Vs), respectively. The refractive index has been determined by variable angle spectroscopic ellipsometry. The refractive index exhibited a significant reduction of its value (from 2.25 to 2 at 1.55 μm) at near IR range where are the main interests of potential applications for nitride based intersubband devices. Reported here values of refractive indices at 1.55 and 1.3 μm are appropriate for fabrication of cladding layers with the required contrast to GaN for intersubband devices. The observed drop of refractive index is attributed to the carrier-induced plasma edge effect, which has been directly observed in reflectance spectrum.

4

(120)-Oriented CdTe/CdMnTe Quantum Well Structures Grown by Molecular Beam Epitaxy

73%

Kutrowski M., Karczewski G., Cywiński G., Surma M., Grasza K., Łusakowska E., Kossut J., Wojtowicz T.

Acta Physica Polonica A

|

1996

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vol. 90

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issue 5

879-882

EN

We report on the MBE growth and magnetooptical studies of (120)-oriented CdTe/CdMnTe quantum well structures. The quality of structures, as evaluated by the photoluminescence line width, was as good as that of the best structures grown in ⟨100⟩ direction. No spin splitting enhancement, expected theoretically, due to the reduction of the antiferromagnetic interaction between Mn ions in CdTe/CdMnTe digital alloy quantum wells grown along ⟨120⟩ direction was observed.

5

Novel CdTe/CdMgTe Graded Quantum Well Structures

73%

Wojtowicz T., Kutrowski M., Karczewski G., Cywiński G., Surma M., Kossut J., Yakovlev D. R., Ossau W., Landwehr G., Kochereshko V.

Acta Physica Polonica A

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1997

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vol. 92

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issue 5

1063-1066

EN

We report on growth and magnetooptical studies of two types of novel CdTe/CdMgTe quantum well structures having a precisely controlled grading of either the quantum well width or the donor concentration in a direction perpendicular to the growth axis. The presence of two-dimensional electron gas of varying concentration produced by the graded modulation doping was evidenced by observation of negatively charged exciton-electron complexes (X¯).

6

Topographical, Magnetic and Optical Studies of (II,Mn)VI Quantum Structures Grown on (Ga,Mn)As

73%

Butkutė R., Aleszkiewicz M., Janik E., Cywiński G., Wojnar P., Däweritz L., Primus J., De Boeck J., Kossut J.

Acta Physica Polonica A

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2003

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vol. 103

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issue 6

649-657

EN

We report on an overgrowth of quantum structures consisting of diluted magnetic semiconductor CdMnTe quantum wells with non-magnetic barriers made of CdMgTe or ZnTe on ferromagnetic MnAs and GaMnAs films by molecular beam epitaxy. Atomic force microscopy images of the quantum structures grown on MnAs demonstrated the existence of two types of regions on the surface: protruded islands with micrometric sizes, surrounded by areas of small-scale roughness. Magnetic force microscopy study of these samples revealed a magnetic domain structure only on the above mentioned islands. The (II,Mn)VI quantum wells grown on GaMnAs films exhibited relatively smooth surface, but no magnetic force microscopy signal was measurable either before or after magnetizing the sample. In the luminescence spectra of all our quantum structures the emission attributed to CdMnTe quantum wells was observed. The influence of magnetization on the luminescence line position was investigated.

7

Waveguide Design for Long Wavelength InGaN Based Laser Diodes

73%

Muzioł G., Turski H., Siekacz M., Sawicka M., Wolny P., Cheze C., Cywiński G., Perlin P., Skierbiszewski C.

Acta Physica Polonica A

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2012

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vol. 122

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issue 6

1031-1033

EN

One-dimensional optical waveguide calculations were performed to study the dependence of waveguide design on confinement factor (Γp) and optical losses (α_i) of nitride laser diodes for emission wavelength ranging from 405 nm to 520 nm. We found that the conventional waveguide design containing GaN waveguide and AlGaN cladding layers known from violet laser diode does not support sufficient confinement of the optical mode for long wavelength devices (λ > 450 nm). We proposed a new design consisting of a thick InGaN waveguide which enhances the confinement. We compared the theoretical predictions with laser diodes grown by plasma assisted molecular beam epitaxy.

8

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts

73%

Czapkiewicz M., Cywiński G., Dybko K., Siekacz M., Wolny P., Gierałtowska S., Guziewicz E., Skierbiszewski C., Wróbel J.

Acta Physica Polonica A

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2012

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vol. 122

|

issue 6

1026-1028

EN

We report on AlGaN/GaN quantum point contacts fabricated by using e-beam lithography and dry ion etching. The tunable nano-constrictions are defined by the integration of side and top gates in a single device. In this configuration, the planar gates are located on the both sides of a quantum channel and the metallic top gates, which cover the active region, are separated from the substrate by an insulating and passivating layers of HfO_2 or Al_2O_3/HfO_2 composite. The properties of devices have been tested at T = 4.2 K. For side gates we have obtained a very small surface leakage current I_g< 10^{-11} A at gate voltages |V_g| < 2 V, however, it is not enough to close the quantum channel. With top gates we have been able to reach the pinch-off voltage at V_g = - 3.5 V at a cost of I_g ≈ 10^{-6} A, which has been identified as a bulk leakage current.

9

Cd_{1-x}Mn_{x}Te Parabolic Quantum Wells

73%

Wojtowicz T., Kutrowski M., Cywiński G., Dynowska E., Karczewski G., Kossut J., Fiederling R., Mackh G., Zehnder U., Ossau W.

Acta Physica Polonica A

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1996

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vol. 90

|

issue 5

977-980

EN

We report on the growth and optical studies of II-VI semiconductor parabolic quantum wells made of Cd_{1-x}Mn_{x}Te for a broad range of quantum well widths and Mn molar fractions x. Photoluminescence excitation spectra revealed several series of peaks equidistant in energy associated with interband optical transitions between harmonic oscillator levels. From the analysis of the spectra the valence band offset Q_{hh} = 0.44±0.1 was determined for the CdTe/Cd_{1-x}Mn_{x}Te system.

10

High Power Continuous Wave Blue InAlGaN Laser Diodes Made by Plasma Assisted MBE

59%

Skierbiszewski C., Siekacz M., Wiśniewski P., Perlin P., Feduniewicz-Żmuda A., Cywiński G., Smalc J., Grzanka S., Grzegory I., Leszczyński M., Porowski S.

Acta Physica Polonica A

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2006

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vol. 110

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issue 3

345-351

EN

Room temperature, continuous wave operation of InGaN multi-quantum wells laser diodes made by rf plasma assisted molecular beam epitaxy at 411 nm wavelength is demonstrated. The threshold current density and voltage were 4.2 kA/cm^2 and 5.3 V, respectively. High optical power output of 60 mW was achieved. The lifetime of these laser diodes exceeds 5 h with 2 mW of optical output power. The laser diodes are fabricated on low dislocation density bulk GaN substrates, at growth conditions which resembles liquid phase epitaxy. We demonstrate that relatively low growth temperatures (600-700°C) pose no intrinsic limitations for fabrication of nitride optoelectronic components by plasma assisted molecular beam epitaxy.

11

Crack Free GaInN/AlInN Multiple Quantum Wells Grown on GaN with Strong Intersubband Absorption at 1.55μm

59%

Cywiński G., Skierbiszewski C., Feduniewicz-Żmuda A., Siekacz M., Nevou L., Doyennette L., Julien F., Prystawko P., Kryśko M., Grzanka S., Grzegory I., Porowski S.

Acta Physica Polonica A

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2006

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vol. 110

|

issue 2

175-181

EN

Crack free GaInN/AlInN multiple quantum wells were grown by rf plasma-assisted molecular beam epitaxy on (0001) GaN/sapphire substrates. The strain-engineering concept was applied to eliminate cracking effect for growth of intersubband structures on GaN. Indium contained ternary compounds of barrier and well layers are contrary strained to the substrate material. A series of crack free GaInN/AlInN intersubband structures on (0001) GaN was fabricated and investigated. The assumed composition and layered structure were confirmed by room temperature photoluminescence and X-ray diffraction measurements. The intersubband measurements were done in multipass waveguide geometry by applying direct intersubband absorption and photoinduced intersubband absorption measurements. The optimized structure design contains forty periods of Si-doped GaInN/AlInN quantum wells and exhibits strong intersubband absorption.

12

Enhancement of Intersubband Absorption in GaInN/AlInN Quantum Wells

59%

Cywiński G., Skierbiszewski C., Siekacz M., Kryśko M., Feduniewicz-Żmuda A., Gladysiewicz M., Kudrawiec R., Misiewicz J., Nevou L., Kheirodin N., Julien F.

Acta Physica Polonica A

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2008

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vol. 114

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issue 5

1093-1099

EN

GaInN/AlInN multiple quantum wells were grown by RF plasma-assisted molecular beam epitaxy on (0001) GaN/sapphire substrates. The strain-engineering concept was applied to eliminate cracking effect and to improve optical parameters of intersubband structures grown on GaN substrates. The high quality intersubband structures were fabricated and investigated as an active region for applications in high-speed devices at telecommunication wavelengths. We observed the significant enhancement of intersubband absorption with an increase in the barrier thickness. We attribute this effect to the better localization of the second electron level in the quantum well. The strong absorption is very important on the way to intersubband devices designed for high-speed operation. The experimental results were compared with theoretical calculations which were performed within the electron effective mass approximation. A good agreement between experimental data and theoretical calculations was observed for the investigated samples.

13

Half-Parabolic Quantum Wells of Diluted Magnetic Semiconductor Cd_{1-x}Mn_{x}Te

59%

Kutrowski M., Wojtowicz T., Cywiński G., Karczewski G., Janik E., Dynowska E., Kossut J., Kossacki P., Fiederling R., Pfeuffer-Jeschke A., Ossau W.

Acta Physica Polonica A

|

1997

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vol. 92

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issue 5

887-890

EN

We report on magnetooptical studies of MBE-grown half-parabolic CdTe/Cd_{x}Mn_{1-x}Te quantum well structures. The value of the valence band offset Q_{v}=0.4 ± 0.05 was determined by comparing energies of optical transitions in the absence of a magnetic field with model calculations. This value was verified by fitting the observed spin splitting of the lowest heavy hole (hh) state. We discuss also the temperature dependence of Q_{v}.

Refine search results

Epitaxial Growths of II-VI Compounds on (110) Substrates

Search for T-Shaped Quantum Wires in CdTe/CdMg(Mn)Te System

Near IR Refractive Index for GaInN Heavily Doped with Silicon

(120)-Oriented CdTe/CdMnTe Quantum Well Structures Grown by Molecular Beam Epitaxy

Novel CdTe/CdMgTe Graded Quantum Well Structures

Topographical, Magnetic and Optical Studies of (II,Mn)VI Quantum Structures Grown on (Ga,Mn)As

Waveguide Design for Long Wavelength InGaN Based Laser Diodes

Electrostatic Gates for GaN/AlGaN Quantum Point Contacts

Cd_{1-x}Mn_{x}Te Parabolic Quantum Wells

High Power Continuous Wave Blue InAlGaN Laser Diodes Made by Plasma Assisted MBE

Crack Free GaInN/AlInN Multiple Quantum Wells Grown on GaN with Strong Intersubband Absorption at 1.55μm

Enhancement of Intersubband Absorption in GaInN/AlInN Quantum Wells

Half-Parabolic Quantum Wells of Diluted Magnetic Semiconductor Cd_{1-x}Mn_{x}Te