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Journal ArticleDOI

Homo- and hetero-epitaxial growth of hexagonal and cubic MgxZn1−x O alloy thin films by pulsed laser deposition technique

TL;DR: In this article, the growth of hexagonal and cubic MgxZn1−xO thin films on lattice matched substrates of c-Al2O3, ZnO, MgO and SrTiO3 was described.
Abstract: In this work, we describe the homo- and hetero-epitaxial growth of hexagonal and cubic MgxZn1−xO thin films on lattice matched substrates of c-Al2O3, ZnO, MgO and SrTiO3. The crystalline quality, composition and epitaxial nature of the alloy films are obtained by x-ray diffraction and Rutherford backscattering spectroscopy (RBS) techniques. The RBS channeling yields are in the range 3–8% for homoepitaxial and hetero-epitaxial thin films. The metal–semiconductor–metal and ultraviolet detectors were fabricated on hexagonal and cubic MgxZn1−xO thin films and the leakage current and UV-visible rejection ratio are correlated with the epitaxial relationship between the film and substrates.
Citations
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Journal ArticleDOI
TL;DR: In this article, a one-dimensional drift-diffusion method was used to model the expected band structure and carrier injection in a hybrid CdZnO quantum-well light emitting diodes.
Abstract: We report on the demonstration of light emission from hybrid CdZnO quantum-well light emitting diodes. A one-dimensional drift-diffusion method was used to model the expected band structure and carrier injection in the device, demonstrating the potential for 90% internal quantum efficiency when a CdZnO quantum well is used. Fabricated devices produced visible electroluminescence that was found to redshift from 3.32 to 3.15 eV as the forward current was increased from 20 to 40 mA. A further increase in the forward current to 50 mA resulted in a saturation of the redshift.

48 citations

Journal ArticleDOI
TL;DR: In this article, a metal-semiconductor−metal photodetector based on this MgZnO film was fabricated, which showed a low dark current of 0.16 pA and lower sub-bandgap photoresponse than the ones with rougher surface in early reports.
Abstract: Cubic Mg0.58Zn0.42O thin films with (100) orientation were grown on cubic MgO substrates. The band gap of the alloy films corresponds to solar blind band. In the case that a MgO buffer layer was employed, the surface roughness was decreased from 38 to 1.6 nm under the same growth conditions. A metal−semiconductor−metal photodetector based on this MgZnO film was fabricated, which showed a low dark current of 0.16 pA and lower sub-bandgap photoresponse than the ones with rougher surface in our early reports.

39 citations

Journal ArticleDOI
TL;DR: In this article, the epitaxial growth of cubic Mg(0.33)Zn(0).(67)O films on MgO (1 0 0) substrate by metalorganic chemical vapor deposition (MOCVD) was reported.

30 citations

Journal ArticleDOI
TL;DR: In this article, structural, optical and cathodoluminescence characterizations of sintered Zn1−xForgeModLoader Mg� Ⴗ₷ Mg▬ O composite materials have been analyzed using X-ray diffraction.
Abstract: This paper reports structural, optical and cathodoluminescence characterizations of sintered Zn1−x Mg x O composite materials. The effects of MgO composition on these film properties have been analyzed. X-ray diffraction (XRD) confirms that all composites are polycrystalline with prominent hexagonal wurtzite structure along two preferred orientations (002) and (101) for the crystallite growth. Above doping content x = 10 %, the formation of the hexagonal ZnMgO alloy phase and the segregation of the cubic MgO phase start. From reflectance and absorption measurements, we determined the band gap energy which tends to increase from 3.287 to 3.827 eV as the doping content increases. This widening of the optical band gap is explained by the Burstein–Moss effect which causes a significant increase of electron concentration (2.89 × 1018−5.19 × 1020 cm−3). The luminescent properties of the Zn1−x Mg x O pellets are studied by cathodoluminescence (CL) at room and liquid nitrogen temperatures under different electron beam excitations. At room temperature, the CL spectra of the Zn1−x Mg x O composites exhibit a dominant broad yellow-green light band at 2.38 eV and two ultraviolet emission peaks at 3.24 and 3.45 eV corresponding to the luminescence of the hexagonal ZnO and ZnMgO structures, respectively. For the doped ZnO samples, it reveals also new red peaks at 1.72 and 1.77 eV assigned to impurities’ emissions. However, the CL spectra recorded at 77 K show the presence of excitonic emission peaks related to recombination of free exciton (X A), neutral donor-bound excitons (D0X) and their phonon replicas. The CL intensity and energy position of the green, red and ultraviolet emission peaks are found to depend strongly on the MgO doping content. The CL intensity of the UV and red emissions is more enhanced than the green light when the MgO content increases. CL imaging analysis shows that the repartition of the emitting centers in Zn1−x Mg x O composites is intimately connected to the film composition and surface morphology.

29 citations

Journal ArticleDOI
TL;DR: In this article, the structural, compositional and optical properties of ZnO/MgxZn1−xO m-plane heterostructures using scanning transmission electron microscopy, laser-assisted atom probe tomography, and micro-photoluminescence were investigated.
Abstract: The structural, compositional, and optical properties of ZnO/MgxZn1−xO m-plane heterostructures are investigated using scanning transmission electron microscopy, laser-assisted atom probe tomography, and micro-photoluminescence. Coupled with electron tomography, atom probe tomography is currently the only technique providing a 3D reconstruction of the position of the atoms of a nanoscale specimen with their chemical nature. The multi-quantum well system investigated exhibits a V-groove grating profile along the a-axis accompanied by the formation of Zn- and Mg-enriched regions corresponding to the edges pointing towards the substrate and towards the upper surface, respectively. The optical signature of these heterostructures has been investigated by performing micro-photoluminescence on atom probe tip specimens. Effective mass calculations based on the 3D microscopy data indicate that the quantum well geometry and barrier composition yield a localization of hole states at the bottom of the V-groove.

24 citations

References
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Journal ArticleDOI
TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

10,260 citations

Book
21 Mar 1997
TL;DR: The physics of gallium nitrides and related compounds GaN growth p-Type GaN obtained by electron beam irradiation n-Type GAN p-type GaN InGaN Zn and Si co-doped GaN double-heterostructure blue and blue green LEDs inGaN single-quantum-well structure LEDs room-temperature pulsed operation of laser diodes emission mechanisms of LEDs and LDs room temperature CW operation of InGAN MQW LDs latest results as discussed by the authors.
Abstract: Physics of gallium nitrides and related compounds GaN growth p-Type GaN obtained by electron beam irradiation n-Type GaN p-Type GaN InGaN Zn and Si co-doped InGaN/AlGaN double-heterostructure blue and blue-green LEDs inGaN single-quantum-well structure LEDs room-temperature pulsed operation of laser diodes emission mechanisms of LEDs and LDs room temperature CW operation of InGaN MQW LDs latest results - lasers with self-organized InGaN quantum dots

3,805 citations

Book ChapterDOI
01 Jan 1994
TL;DR: Pulsed laser deposition of high-temperature superconducting thin films for active and passive device applications is discussed in this article, with a focus on the commercial scale-up of Pulsed Laser Deposition.
Abstract: Partial table of contents: History and Fundamentals of Pulsed Laser Deposition (J. Cheung). Diagnostics and Characteristics of Laser--Produced Plasmas (D. Geohegan). Particulates Generated by Pulsed Laser Ablation (L.--C. Chen). Angular Distribution of Ablated Material (K. Saenger). Film Nucleation and Film Growth in Pulsed Laser Deposition of Ceramics (J. Horwitz & J. Sprague). Processes Characteristics and Film Properties in Pulsed Laser Plasma Deposition (S. Metev). Commercial Scale--Up of Pulsed Laser Deposition (J. Greer). Pulsed Laser Deposition: Future Trends (T. Venkatesan). Comparison of Vacuum Deposition Techniques (G. Hubler). Pulsed Laser Deposition of High--Temperature Superconducting Thin Films for Active and Passive Device Applications (R. Muenchausen & X. Wu). Pulsed Laser Deposition of Metals (J. Kools). Appendix. References. Index.

3,228 citations

Journal ArticleDOI
TL;DR: In this paper, the spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry-phase approach to polarization in solids.
Abstract: The spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry-phase approach to polarization in solids. The piezoelectric constants are found to be up to ten times larger than in conventional III-V and II-VI semiconductor compounds, and comparable to those of ZnO. Further properties at variance with those of conventional III-V compounds are the sign of the piezoelectric constants (positive as in II-VI compounds) and the very large spontaneous polarization.

2,785 citations

Journal ArticleDOI
TL;DR: Wurtzitic ZnO is a widebandgap semiconductor which has many applications, such as piezoelectric transducers, varistors, phosphors, and transparent conducting films as discussed by the authors.
Abstract: Wurtzitic ZnO is a wide-bandgap (3.437 eV at 2 K) semiconductor which has many applications, such as piezoelectric transducers, varistors, phosphors, and transparent conducting films. Most of these applications require only polycrystalline material; however, recent successes in producing large-area single crystals have opened up the possibility of producing blue and UV light emitters, and high-temperature, high-power transistors. The main advantages of ZnO as a light emitter are its large exciton binding energy (60 meV), and the existence of well-developed bulk and epitaxial growth processes; for electronic applications, its attractiveness lies in having high breakdown strength and high saturation velocity. Optical UV lasing, at both low and high temperatures, has already been demonstrated, although efficient electrical lasing must await the further development of good, p-type material. ZnO is also much more resistant to radiation damage than are other common semiconductor materials, such as Si, GaAs, CdS, and even GaN; thus, it should be useful for space applications.

2,573 citations