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1

Fabrication and Properties of Amorphous Zinc Oxynitride Thin Films

100%

Kaczmarski J., Borysiewicz M., Pągowska K., Kamińska E.

Acta Physica Polonica A

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2016

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vol. 129

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issue 1

150-152

EN

Zn-O-N thin films fabricated by reactive radio frequency magnetron sputtering have been investigated for their compositional, structural, transport and optical properties. In contrast to processes in which the reaction for either the oxide or the nitride is dominant, the multireaction process yields a substantially amorphous films with the Hall mobility within the range from 15 to 80 cm²/(V s). In addition, it has been observed that the Hall mobility increases for Zn-O-N. Since it has a narrower bandgap than ZnO, it is put forward that the high mobility is due to the valence band maximum in this material lying above the trap states in the gap commonly observable in ZnO. These traps originate from oxygen vacancies and are localized at the bottom of the band gap influencing the carrier mobility.

2

Stopping Power and Energy Straggling of Channeled He-Ions in GaN

76%

Turos A., Ratajczak R., Pągowska K., Nowicki L., Stonert A., Caban P.

Acta Physica Polonica A

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2011

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vol. 120

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issue 1

163-166

EN

GaN epitaxial layers are usually grown on sapphire substrates. To avoid disastrous effect of the large lattice mismatch a thin polycrystalline nucleation layer is grown at 500°C followed by the deposition of thick GaN template at much higher temperature. Remnants of the nucleation layer were visualized by transmission electron microscopy as defect agglomeration at the GaN/sapphire interface and provide a very useful depth marker for the measurement of channeled ions stopping power. Random and aligned spectra of He ions incident at energies ranging from 1.7 to 3.7 MeV have been measured and evaluated using the Monte Carlo simulation code McChasy. Impact parameter dependent stopping power has been calculated for channeling direction and its parameters have been adjusted according to experimental data. For virgin, i.e. as grown, samples, the ratio of channeled to random stopping power is constant and amounts to 0.7 in the energy range studied. Defects produced by ion implantation largely influence the stopping power. For channeled ions the variety of possible trajectories leads to different energy loss at a given depth, thus resulting in much larger energy straggling than that for the random path. Beam energy distributions at different depths have been calculated using the McChasy code. They are significantly broader than those predicted by the Bohr formula for random direction.

3

Response of ZnO/GaN Heterostructure to Ion Irradiation

64%

Barcz A., Pągowska K., Kozubal M., Guziewicz E., Borysiewicz M., Dyczewski J., Jakieła R., Ratajczak J., Snigurenko D., Dynowska E.

Acta Physica Polonica A

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2015

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vol. 128

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issue 5

832-835

EN

In this paper we report on the analysis of Al⁺-implanted ZnO/GaN bilayers in search for the damage production mechanism and possible ion mixing. 100 nm or 200 nm thick ZnO epitaxial layers were grown on GaN substrates by either sputter deposition or atomic layer deposition technique followed by adequate annealing. Ion irradiations of ZnO/GaN were carried out at room temperature using 200 keV Al⁺ ions with fluences of 2×10¹⁵ and 10¹⁶ at./cm². Unprocessed and irradiated samples were characterized by the Rutherford backscattering spectrometry in channeling geometry (RBS\c), X-ray diffraction and transmission electron microscopy. Additionally, secondary ion mass spectrometry was employed for the aforementioned samples as well as for the implanted samples subjected to further annealing. It was found that the damage distributions in ZnO/GaN differ considerably from the corresponding defect profiles in the bulk ZnO and GaN crystals, most probably due to an additional strain originating from the lattice mismatch. Amount of intermixing appears to be relatively small; apparently, efficient recombination prevents foreign atoms to relocate to large distances.

4

RBS/Channeling and TEM Study of Damage Buildup in Ion Bombarded GaN

64%

Pągowska K., Ratajczak R., Stonert A., Turos A., Nowicki L., Sathish N., Jóźwik P., Muecklich A.

Acta Physica Polonica A

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2011

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vol. 120

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issue 1

153-155

EN

A systematic study on structural defect buildup in 320 keV Ar-ion bombarded GaN epitaxial layers has been reported, by varying ion fluences ranged from 5 × 10^{12} to 1 × 10^{17} at./cm^2. 1 μm thick GaN epitaxial layers were grown on sapphire substrates using the metal-organic vapor phase epitaxy technique. Rutherford backscattering/channeling with 1.7 MeV^4He beam was applied for analysis. As a complementary method high resolution transmission electron microscopy has been used. The later has revealed the presence of extended defects like dislocations, faulted loops and stacking faults. New version of the Monte Carlo simulation code McChasy has been developed that makes it possible to analyze such defects on the basis of the bent channel model. Damage accumulation curves for two distinct types of defects, i.e. randomly displaced atoms and extended defects (i.e. bent channel) have been determined. They were evaluated in the frame of the multistep damage accumulation model, allowing numerical parameterization of defect transformations occurring upon ion bombardment. Displaced atoms buildup is a three-step process for GaN, whereas extended defect buildup is always a two-step process.

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4 Acta Physica Polonica A

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4 Pągowska K.

2 Borysiewicz M.

2 Nowicki L.

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2 Turos A.

1 Barcz A.

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1 Dyczewski J.

1 Dynowska E.

1 Guziewicz E.

1 Jakieła R.

1 Jóźwik P.

1 Kaczmarski J.

1 Kamińska E.

1 Kozubal M.

1 Muecklich A.

1 Ratajczak J.

1 Sathish N.

1 Snigurenko D.

Fabrication and Properties of Amorphous Zinc Oxynitride Thin Films

Stopping Power and Energy Straggling of Channeled He-Ions in GaN

Response of ZnO/GaN Heterostructure to Ion Irradiation

RBS/Channeling and TEM Study of Damage Buildup in Ion Bombarded GaN