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1

Improving optical and morphological properties of Mn-dopedZnO via Ar ion sputtering followed by high-temperature UHV annealing

Zehar Elhachemi, Ouerdane Abdallah, Chetti Boualem, Coruh Ali

Materials Science Poland

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2023

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Vol. 41, No. 2

325--338

EN

Using the ultrasonic spray pyrolysis technique, pure (ZnO) and manganese (4at%)-doped zinc oxide (ZnMnO) thin films were synthesized and treated with Ar+ sputtering in the UHV (ultra-high vacuum) system. In this regard, XRD (X-ray diffraction), XPS (X-ray photoelectron spectroscopy), PL (photoluminescence), and AFM (atomic force microscopy) techniques were applied to investigate the electronic and photonic properties of ZnO. XRD and XPS allowed us to identify the successful incorporation of Mn as a substitute for Zn, while PL and AFM images reveal a high tendency for crystalline grains on theZnMnO surface to aggregate to form small grains. However, bandgap narrowing, a redshift with considerable fluctuations in excitonic emission, and a perfect quenching of visible emission (400–640 nm) were observed. Investigations into defect-related emission in ZnMnO and ZnO compounds were conducted. The PL spectra of the prepared samples were measured and analyzed using Gaussian fitting. The PL of undoped ZnOexhibited an intense broad band with a peak at 550 nm. Two effects were shown to occur as a result of Mn doping: (i) a sharp quenching of self-activated PL with a progressive red-shift of the quenching’s spectral boundary; (ii) the appearance of a new emission band with a peak at 1.64 eV (756 nm), which dominates the PL spectrum and is noted in a band diagram; as well as a slight shift in the main line of ZnO, which is located at energy 3.275 eV (378.57nm).

2

Determination of the band structure diagram of semiconductor heterostructures applied in photovoltaics

Bogaczewicz Rafał Antoni, Popko Ewa, Gwóźdź Katarzyna Renata

Optica Applicata

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2021

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Vol. 51, nr 1

135--145

EN

Recently it has been found that the heterostructures of n-ZnO/p-Si are promising photovoltaic alternatives to silicon homojunctions. It is well known that the energy band diagram of a heterostructure is crucial for the understanding of its operation. This paper analyzes the ZnO/p-Si heterostructure band by using free AMPS-1D computer program simulations. The obtained numerical results are compared with theoretical calculations based on the depletion region approximation model and the Poisson’s equation for electric potential. The results of the simulation are also compared with the experimental C-V characteristics of the test n-ZnO/p-Si heterostructure. The simulated C-V characteristics is qualitatively consistent with the experimental C-V curve, which confirms the correctness of the determined band diagram of the n-ZnO/p-Si heterostructure.

3

Określanie schematów pasmowych struktur MOS na podłożu SiC(4H)

Piskorski K., Przewłocki H. M., Bakowski M.

Przegląd Elektrotechniczny

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2014

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R. 90, nr 9

86-90

PL

W celu określenia schematów pasmowych struktur MOS wykonanych na podłożu z węglika krzemu SiC(4H) wykorzystano szereg technik charakteryzacji: elektrycznych, optycznych oraz fotoelektrycznych. Szczególnie przydatne są pomiary fotoelektryczne, które pozwalają na wyznaczenie wysokości barier potencjału na powierzchniach granicznych dielektryka, jak również pozwalają na określenie położenia energetycznego stanów powierzchniowych na granicy SiO2/SiC. Praca przedstawia wyniki pomiarów wykonanych na kondensatorach MOS z aluminiową bramką Al oraz z warstwą dielektryka wykonaną w dwóch różnych technologiach (chemiczne osadzanie i termiczne utlenianie).

EN

In order to determine band diagrams of the MOS structures made on SiC(4H) substrate several measurement techniques were used: electrical, optical and photoelectric methods. Particularly photoelectric methods are useful since they allow determination of barrier heights at the both dielectric interfaces. In this work measurement results performed on MOS capacitors with aluminum metal gate and with different dielectric layers (chemical deposition and thermal oxidation) are presented.

4

Band diagram determination of MOS structures with different gate materials on 3C-SiC substrate

Piskorski K., Przewlocki H. M., Esteve R., Bakowski M.

Opto-Electronics Review

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2012

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Vol. 20, No. 1

67-74

EN

MOS capacitors were fabricated on 3C-SiC n-type substrate (001) with a 10-µm N-type epitaxial layer. An SiO2 layer of the thickness tox ≈ 55 nm was deposited by PECVD. Circular Al, Ni, and Au gate contacts 0.7 mm in diameter were formed by ion beam sputtering and lift-off. Energy band diagrams of the MOS capacitors were determined using the photoelectric, electric, and optical measurement methods. Optical method (ellipsometry) was used to determine the gate and dielectric layer thicknesses and their optical indices: the refraction n and the extinction k coefficients. Electrical method of C = ƒ (VG) characteristic measurements allowed to determine the doping density ND and the flat band voltage VFB in the semiconductor. Most of the parameters which were necessary for the construction of the band diagrams and for determination of the basic physical properties of the structures (e.g. the effective contact potential difference ΦMS) were measured by several photoelectric methods and calculated using the measurement data. As a result, complete energy band diagrams have been determined for MOS capacitors with three different gate materials and they are demonstrated for two different gate voltages VG: for the flat-band in the semiconductor (VG = VFB) and for the flat-band in the dielectric (VG = VG0).

5

Electrical and photoelectric characterization of the MOS structures on 3C-SiC substrate

Piskorski K., Przewłocki H. M., Esteve R., Bakowski M.

Optica Applicata

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2011

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Vol. 41, nr 2

295--305

EN

In this work results are presented of the electrical and photoelectric measurements of MOS capacitors, consisting of an Al gate of thickness 25 nm, SiO2 insulator of thickness 60 nm, and n-doped 3C-SiC. Many different measurement techniques are employed in order to completely define all parameters of the band diagram of the MOS structure, which is the main goal of these investigations.

6

Kompleksowa charakteryzacja struktur elektronicznych na podłożach SiC metodami fotoelektrycznymi, elektrycznymi i optycznymi

Przewłocki H. M., Gutt T., Piskorski K., Rzodkiewicz W., Borowicz P., Esteve R., Bakowski M.

Elektronika : konstrukcje, technologie, zastosowania

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2011

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Vol. 52, nr 9

49-52

PL

Przedstawiono wyniki kompleksowej charakteryzacji serii różnych struktur MOS wykonanych na podłożach 3C-SiC. Struktury te różniły się między sobą sposobem wytworzenia warstwy SiO₂ (PECVD oraz utlenianie termiczne w wilgotnym tlenie) oraz materiałem bramki (Al, Au, Ni i poli-Si). Charakteryzację wykonano za pomocą zespołu metod fotoelektrycznych, elektrycznych i optycznych.

EN

The results of the comprehensive characterization of a MOS structures made on 3C-SiC substrate are presented The investigated structures differed in the way the dielectric layer was formed (PECVD, thermal oxidation) and in the gate material (Al. Ni, Au and poly-Si) Many different measurement techniques were employed: photoelectric, electric and optical methods.