Photoluminescence and Raman spectra in Ga-doped ZnO layers on sapphire

2007 ◽  
Vol 1035 ◽  
Author(s):  
Michael A. Reshchikov ◽  
S. Nagata ◽  
J. Xie ◽  
B. Hertog ◽  
A. Osinsky
Keyword(s):  
Raman Spectra ◽  
Room Temperature ◽  
Molecular Beam ◽  
Exciton Peak ◽  
Deep Acceptor ◽  
Sapphire Substrates ◽  
Related Defect ◽  
Doped Zno ◽  
Ga Doping ◽  
Zn Vacancy

AbstractGa-doped ZnO layers were grown on sapphire substrates by molecular beam epitaxy (MBE). Low-temperature photoluminescence (PL) and room-temperature Raman spectra were investigated. Defect-related modes at 277 and 510 cm−1 appeared in the Raman spectrum for Ga-doped layers. The PL spectrum is dominated by a donor-bound exciton peak at 3.356 eV. A weak yellow luminescence (YL) band peaking at 2.1-2.2 eV was studied in detail. It shifted to higher photon energies (up to 0.1 eV) with increasing excitation intensity. The YL band is attributed to transitions from shallow donors to a deep acceptor. The acceptor is thought to be a Zn vacancy-related defect because the intensity of the YL band decreased dramatically with Ga doping.

Zn vacancy induced ferromagnetism in K doped ZnO

2015 ◽  
Vol 3 (45) ◽  
pp. 11953-11958 ◽  
Author(s):  
Yiren Wang ◽  
Jingyuan Piao ◽  
Guozhong Xing ◽  
Yunhao Lu ◽  
Zhimin Ao ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lattice Distortion ◽  
Room Temperature Ferromagnetism ◽  
Experimental Studies ◽  
Defect Complex ◽  
Doped Zno ◽  
Zn Vacancy

K doped ZnO shows room temperature ferromagnetism from both theoretical and experimental studies. This ferromagnetism is mainly attributed to the formation of the Zn vacancy. The K dopants can stabilize the Zn vacancy by forming a defect complex and K substitution can induce magnetism via lattice distortion.

Ferromagnetism properties of Er-doped ZnO: a GGA + U study

RSC Advances ◽  
2016 ◽  
Vol 6 (109) ◽  
pp. 107865-107870 ◽  
Author(s):  
Sanjun Wang ◽  
Xiaobo Shi ◽  
Jinming Li
Keyword(s):  
Magnetic Moment ◽  
First Principles ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
First Principles Calculation ◽  
Doped Zno ◽  
Er Doped ◽  
Zn Vacancy

Our first-principles calculation finds that only the Zn vacancy can induce a 1.0 μB magnetic moment in Er-doped ZnO, which comes from the unpaired 2p electrons at the ligand O atom and results in the room-temperature ferromagnetism property of ZnO.

Growth and characterization of Ga-doped ZnO layers on a-plane sapphire substrates grown by molecular beam epitaxy

2002 ◽  
Vol 237-239 ◽  
pp. 538-543 ◽  
Author(s):  
Hiroyuki Kato ◽  
Michihiro Sano ◽  
Kazuhiro Miyamoto ◽  
Takafumi Yao
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Sapphire Substrates ◽  
Doped Zno

Growth of non-polar a-plane and cubic InN on r-plane sapphire by molecular beam epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
Hai Lu ◽  
William J. Schaff ◽  
Lester F. Eastman ◽  
Volker Cimalla ◽  
Joerg Pezoldt ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Hexagonal Phase ◽  
Electronic Devices ◽  
Heteroepitaxial Growth ◽  
Sapphire Substrates ◽  
Wurtzite Hexagonal Phase ◽  
Cubic Structure ◽  
Potential Improvement

ABSTRACTGrowth of non-polar III-nitrides has been an important subject recently due to its potential improvement on the efficiency of III-nitride-based opto-electronic devices. Despite study of non-polar GaN and GaN-based heterostructures, there are few reports on epitaxial growth of non-polar InN, which is also an important component of the III-nitride system. In this study, we report heteroepitaxial growth of non-polar InN on r-plane sapphire substrates using plasma-assisted molecular beam epitaxy. It is found that when a GaN buffer is used, the following InN film appears to be non-polar (1120) a-plane which follows the a-plane GaN buffer. The room temperature Hall mobility of undoped a-plane InN is around 250 cm2/Vs with a carrier concentration around 6×1018 cm-3. Meanwhile, if InN film is directly deposited on r-plane sapphire without any buffer, the InN layer is found to consist of a predominant zincblende (cubic) structure along with a fraction of the wurtzite (hexagonal) phase with increasing content with proceeding growth.

Strong room-temperature ferromagnetism of high-quality lightly Mn-doped ZnO grown by molecular beam epitaxy

2012 ◽  
Vol 112 (5) ◽  
pp. 053708 ◽  
Author(s):  
Zheng Zuo ◽  
Huimei Zhou ◽  
Mario J. Olmedo ◽  
Jieying Kong ◽  
Ward P. Beyermann ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Room Temperature Ferromagnetism ◽  
High Quality ◽  
Doped Zno ◽  
Mn Doped

Excitons bound to structural defects in GaN

2001 ◽  
Vol 693 ◽  
Author(s):  
M. A. Reshchikov ◽  
D. Huang ◽  
F. Yun ◽  
H. Morkoç ◽  
R. J. Molnar ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Structural Defects ◽  
Excitation Density ◽  
High Quality ◽  
Pl Spectra ◽  
Sapphire Substrates ◽  
Uv Illumination ◽  
Increasing Temperature

AbstractWe analyzed the photoluminescence (PL) spectra of undoped GaN films grown by molecular beam epitaxy on sapphire substrates. While the PL spectra from high-quality samples contain free and bound exciton peaks only, the spectra from some samples involve sharp unidentified peaks in the energy range of 3.0 – 3.45 eV, specifically at 3.21, 3.32, 3.36, and 3.42 eV. We attribute these peaks to excitons bound to defects because of the linear and sometimes superlinear increase in their intensity with excitation density without saturation up to 100 W/cm2. With increasing temperature these peaks quench in a well-known fashion similar to that for excitons. In order to relate the observed peaks to the structural defects, we etched selected samples in hot H3PO4 acid or, alternatively, with photo-electrochemical (PEC) etching at room temperature in the presence of UV-illumination in a dilute KOH solution. In the former case the dislocations were etched leaving etched pits on the surface, while in the latter case the dislocations remained unetched due to a deficit of photogenerated holes at dislocation sites. We found that the 3.42 eV peak disappeared after both hot wet and PEC etching suggesting that the associated defect is at the GaN surface. Peaks at 3.21 and 3.36 eV could be enhanced greatly by PEC etching, which were correlated to bulk dislocations.

Zn vacancy induced room-temperature ferromagnetism in Mn-doped ZnO

2007 ◽  
Vol 91 (6) ◽  
pp. 062113 ◽  
Author(s):  
Wensheng Yan ◽  
Zhihu Sun ◽  
Qinghua Liu ◽  
Zhongrui Li ◽  
Zhiyun Pan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Doped Zno ◽  
Mn Doped ◽  
Zn Vacancy

Effect of in Concentration on the Optical Lattice Vibrations in Quaternary AlxInyGa1-x-yN Alloys

2012 ◽  
Vol 501 ◽  
pp. 281-285
Author(s):  
A.I. Aljameel ◽  
H. Abu Hassan ◽  
S.S Ng
Keyword(s):  
Mole Fraction ◽  
Optical Lattice ◽  
Room Temperature ◽  
Molecular Beam ◽  
Buffer Layers ◽  
Lattice Vibrations ◽  
High Quality ◽  
Long Wavelength ◽  
Sapphire Substrates ◽  
Mode Behavior

Fourier transform infrared (FTIR) spectroscopy has been utilized to measure long-wavelength optical lattice vibrations of high-quality quaternary AlxlnyGa1-x-yN thin films at room temperature. The AlxlnyGa1-x-yN films were grown on c-plane (0001) sapphire substrates with AlN as buffer layers using plasma assisted molecular beam epitaxy (PA-MBE) technique with indium (In) mole fraction y = 0.0 to 0.10 and constant aluminium (Al) mole fraction x = 0.06. The experimental results indicated that the AlxlnyGa1-x-yN alloys had two-mode behavior, for the A1 (LO) and E1 (TO) modes.

Photoluminescence and Magnetic Properties of Undoped and (Mn, Co) co-doped ZnO Nanoparticles

2020 ◽  
Vol 16 (4) ◽  
pp. 655-666
Author(s):  
Mona Rekaby
Keyword(s):  
Magnetic Properties ◽  
Zno Nanoparticles ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Structural Defects ◽  
Ferromagnetic Behavior ◽  
Secondary Phases ◽  
Antiferromagnetic Ordering ◽  
Doped Zno ◽  
Co Doped

Objective: The influence of Manganese (Mn2+) and Cobalt (Co2+) ions doping on the optical and magnetic properties of ZnO nanoparticles was studied. Methods: Nanoparticle samples of type ZnO, Zn0.97Mn0.03O, Zn0.96Mn0.03Co0.01O, Zn0.95Mn0.03 Co0.02O, Zn0.93Mn0.03Co0.04O, and Zn0.91Mn0.03Co0.06O were synthesized using the wet chemical coprecipitation method. Results: X-ray powder diffraction (XRD) patterns revealed that the prepared samples exhibited a single phase of hexagonal wurtzite structure without any existence of secondary phases. Transmission electron microscope (TEM) images clarified that Co doping at high concentrations has the ability to alter the morphologies of the samples from spherical shaped nanoparticles (NPS) to nanorods (NRs) shaped particles. The different vibrational modes of the prepared samples were analyzed through Fourier transform infrared (FTIR) measurements. The optical characteristics and structural defects of the samples were studied through Photoluminescence (PL) spectroscopy. PL results clarified that Mn2+ and Co2+ doping quenched the recombination of electron-hole pairs and enhanced the number of point defects relative to the undoped ZnO sample. Magnetic measurements were carried out at room temperature using a vibrating sample magnetometer (VSM). (Mn, Co) co-doped ZnO samples exhibited a ferromagnetic behavior coupled with paramagnetic and weak diamagnetic contributions. Conclusion: Mn2+ and Co2+ doping enhanced the room temperature Ferromagnetic (RTFM) behavior of ZnO. In addition, the signature for antiferromagnetic ordering between the Co ions was revealed. Moreover, a strong correlation between the magnetic and optical behavior of the (Mn, Co) co-doped ZnO was analyzed.

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