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Dłużewski P., Domagala J.Z.♦, Kret S.♦, Jarosz D.♦, Kryśko M.♦, Teisseyre H.♦, Phase-transition critical thickness of rocksalt MgxZn1−xO layers,
The Journal of Chemical Physics, ISSN: 0021-9606, DOI: 10.1063/5.0042415, Vol.154, pp.154701-1-8, 2021Streszczenie: The rocksalt structure of ZnO has a very promising bandgap for optoelectronic applications. Unfortunately, this high-pressure phase is unstable under ambient conditions. This paper presents experimental results for rocksalt-type ZnO/MgO superlattices and theoretical considerations of the critical thickness of MgxZn1−xO layers. The correlations between the layer/spacer thickness ratio, elastic strain, chemical composition, and critical thickness are analyzed. The Matthews and Blakeslee model is revisited to find analytic conditions for the critical layer thickness resulting in phase transition. Our analysis shows that due to the decrease in misfit stresses below some critical limit, the growth of multiple quantum wells composed of rocksalt ZnO layers and MgO spacers is possible only for very large layer/spacer thickness ratios. Afiliacje autorów:
Dłużewski P. | - | IPPT PAN | Domagala J.Z. | - | inna afiliacja | Kret S. | - | Institute of Physics, Polish Academy of Sciences (PL) | Jarosz D. | - | Institute of High Pressure Physics, Polish Academy of Sciences (PL) | Kryśko M. | - | inna afiliacja | Teisseyre H. | - | Institute of Physics, Polish Academy of Sciences (PL) |
| | 100p. |
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Teisseyre H.♦, Kaminska A.♦, Birner S.♦, Young T.D., Suchocki A.♦, Kozanecki A.♦, Influence of hydrostatic pressure on the built-in electric field in ZnO/ZnMgO quantum wells,
JOURNAL OF APPLIED PHYSICS, ISSN: 0021-8979, DOI: 10.1063/1.4953251, Vol.119, pp.215702-1-8, 2016Streszczenie: We used high hydrostatic pressure to perform photoluminescence measurements on polar ZnO/ZnMgO quantum well structures. Our structure oriented along the c-direction (polar direction) was grown by plasma-assisted molecular beam epitaxy on a-plane sapphire. Due to the intrinsic electric field, which exists in polar wurtzite structure at ambient pressure, we observed a red shift of the emission related to the quantum-confined Stark effect. In the high hydrostatic pressure experiment, we observed a strong decrease of the quantum well pressure coefficients with increased thickness of the quantum wells. Generally, a narrower quantum well gave a higher pressure coefficient, closer to the band-gap pressure coefficient of bulk material 20 meV/GPa for ZnO, while for wider quantum wells it is much lower. We observed a pressure coefficient of 19.4 meV/GPa for a 1.5 nm quantum well, while for an 8 nm quantum well the pressure coefficient was equal to 8.9 meV/GPa only. This is explained by taking into account the pressure-induced increase of the strain in our structure. The strain was calculated taking in to account that in-plane strain is not equal (due to fact that we used a-plane sapphire as a substrate) and the potential distribution in the structure was calculated self-consistently. The pressure induced increase of the built-in electric field is the same for all thicknesses of quantum wells, but becomes more pronounced for thicker quantum wells due to the quantum confined Stark effect lowering the pressure coefficients. Słowa kluczowe: Piezoelectric fields, Quantum wells, Polarization, Zinc oxide films, High pressure Afiliacje autorów:
Teisseyre H. | - | Institute of Physics, Polish Academy of Sciences (PL) | Kaminska A. | - | Institute of Physics, Polish Academy of Sciences (PL) | Birner S. | - | nextnano GmbH (DE) | Young T.D. | - | IPPT PAN | Suchocki A. | - | Institute of Physics, Polish Academy of Sciences (PL) | Kozanecki A. | - | inna afiliacja |
| | 30p. |
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Teisseyre H.♦, Boćkowski M.♦, Young T.D., Grzanka Sz.♦, Zhydachevskii Y.♦, Grzegory I.♦, Kozanecki A.♦, A monolithic white-light LED based on GaN doped with Be,
Advances in Science and Technology, ISSN: 1662-0356, DOI: 10.4028/www.scientific.net/AST.93.264, Vol.93, pp.264-269, 2014Streszczenie: In this communication, the use of gallium nitride doped with beryllium as an efficient converter for white light emitting diode is proposed. Until now beryllium in this material was mostly studied as a potential p-type dopant. Unfortunately, the realization of p-type conductivity in such a way seems impossible. However, due to a very intensive yellow emission, bulk crystals doped with beryllium can be used as light converters. In this communication, it is demonstrated that realisation of such diode is possible and realisation of a colour rendering index is close to that necessary for white light emission. Słowa kluczowe: Beryllium, Gallium Nitride (GaN), Light Emitting Diode (LED), Optical Converters Afiliacje autorów:
Teisseyre H. | - | Institute of Physics, Polish Academy of Sciences (PL) | Boćkowski M. | - | Institute of High Pressure Physics, Polish Academy of Sciences (PL) | Young T.D. | - | IPPT PAN | Grzanka Sz. | - | inna afiliacja | Zhydachevskii Y. | - | Institute of Physics, Polish Academy of Sciences (PL) | Grzegory I. | - | Institute of High Pressure Physics, Polish Academy of Sciences (PL) | Kozanecki A. | - | inna afiliacja |
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Teisseyre H.♦, Suski T.♦, Łepkowski S.P.♦, Perlin P.♦, Jurczak G., Dłużewski P., Daudin B.♦, Grandjean N.♦, Strong electric field and nonuniformity effects in GaN/AlN quantum dots revealed by high pressure studies,
APPLIED PHYSICS LETTERS, ISSN: 0003-6951, DOI: 10.1063/1.2219381, Vol.89, No.5, pp.51902-1-3, 2006Streszczenie: The photoluminescence (PL) from GaN quantum dots (QDs) embedded in AlN has been investigated under hydrostatic pressure. The measured pressure coefficient of emitted light energy [dE / dP] shows a negative value, in contrast with the positive pressure coefficient of the GaN band gap. We also observed that increasing pressure leads to a significant decrease of the light emission intensity and an asymmetric broadening of the PL band. All these effects are related to the pressure-induced increase of the built-in electric field. A comparison is made between experimental results and the proposed theoretical model which describes the pressure behavior of nitride QDs. Słowa kluczowe: III-V semiconductor, Quantum dot, Piezoelectricity, Photoluminescence Afiliacje autorów:
Teisseyre H. | - | Institute of Physics, Polish Academy of Sciences (PL) | Suski T. | - | Institute of High Pressure Physics, Polish Academy of Sciences (PL) | Łepkowski S.P. | - | Institute of High Pressure Physics, Polish Academy of Sciences (PL) | Perlin P. | - | Institute of High Pressure Physics, Polish Academy of Sciences (PL) | Jurczak G. | - | IPPT PAN | Dłużewski P. | - | IPPT PAN | Daudin B. | - | CNRS (FR) | Grandjean N. | - | École Polytechnique Federale de Lausanne (CH) |
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