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Wei W, Yang Y, Peng Y, Maraj M, Sun W. Optical and Electrical Properties of Al xGa 1-xN/GaN Epilayers Modulated by Aluminum Content. Molecules 2024; 29:1152. [PMID: 38474664 DOI: 10.3390/molecules29051152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/22/2023] [Accepted: 01/04/2024] [Indexed: 03/14/2024] Open
Abstract
AlGaN-based LEDs are promising for many applications in deep ultraviolet fields, especially for water-purification projects, air sterilization, fluorescence sensing, etc. However, in order to realize these potentials, it is critical to understand the factors that influence the optical and electrical properties of the device. In this work, AlxGa1-xN (x = 0.24, 0.34, 0.47) epilayers grown on c-plane patterned sapphire substrate with GaN template by the metal organic chemical vapor deposition (MOCVD). It is demonstrated that the increase of the aluminum content leads to the deterioration of the surface morphology and crystal quality of the AlGaN epitaxial layer. The dislocation densities of AlxGa1-xN epilayers were determined from symmetric and asymmetric planes of the ω-scan rocking curve and the minimum value is 1.01 × 109 cm-2. The (101¯5) plane reciprocal space mapping was employed to measure the in-plane strain of the AlxGa1-xN layers grown on GaN. The surface barrier heights of the AlxGa1-xN samples derived from XPS are 1.57, 1.65, and 1.75 eV, respectively. The results of the bandgap obtained by PL spectroscopy are in good accordance with those of XRD. The Hall mobility and sheet electron concentration of the samples are successfully determined by preparing simple indium sphere electrodes.
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Affiliation(s)
- Wenwang Wei
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
- Guangxi Key Laboratory of Calcium Carbonate Resources Comprehensive Utilization, College of Materials and Chemical Engineering, Hezhou University, Hezhou 542899, China
| | - Yanlian Yang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Yi Peng
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Mudassar Maraj
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Wenhong Sun
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
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Wei W, Peng Y, Yang Y, Xiao K, Maraj M, Yang J, Wang Y, Sun W. Study of Defects and Nano-patterned Substrate Regulation Mechanism in AlN Epilayers. Nanomaterials (Basel) 2022; 12:3937. [PMID: 36432223 PMCID: PMC9695674 DOI: 10.3390/nano12223937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/01/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
The high crystal quality and low dislocation densities of aluminum nitride (AlN) grown on flat and nano-patterned sapphire substrate that are synthesized by the metal-organic chemical vapor deposition (MOCVD) method are essential for the realization of high-efficiency deep ultraviolet light-emitting diodes. The micro-strains of 0.18 × 10-3 cm-2 for flat substrate AlN and 0.11 × 10-3 cm-2 for nano-patterned substrate AlN are obtained by X-ray diffractometer (XRD). The screw and edge dislocation densities of samples are determined by XRD and transmission electron microscope (TEM), and the results indicate that the nano-patterned substrates are effective in reducing the threading dislocation density. The mechanism of the variation of the threading dislocation in AlN films grown on flat and nano-patterned substrates is investigated comparatively. The etch pit density (EPD) determined by preferential chemical etching is about 1.04 × 108 cm-2 for AlN grown on a nano-patterned substrate, which is slightly smaller than the results obtained by XRD and TEM investigation. Three types of etch pits with different sizes are all revealed on the AlN surface using the hot KOH etching method.
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Affiliation(s)
- Wenwang Wei
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
- College of Materials and Chemical Engineering, Hezhou University, Hezhou 542899, China
| | - Yi Peng
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Yanlian Yang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Kai Xiao
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Mudassar Maraj
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Jia Yang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Yukun Wang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
| | - Wenhong Sun
- Research Center for Optoelectronic Materials and Devices, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
- MOE Key Laboratory of New Processing Technology for Nonferrous Metals and the Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials, Guangxi University, Nanning 530004, China
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Maraj M, Min L, Sun W. Reliability Analysis of AlGaN-Based Deep UV-LEDs. Nanomaterials (Basel) 2022; 12:nano12213731. [PMID: 36364507 PMCID: PMC9657871 DOI: 10.3390/nano12213731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 09/24/2022] [Accepted: 10/19/2022] [Indexed: 05/27/2023]
Abstract
The current pandemic crisis caused by SARS-CoV-2 has also pushed researchers to work on LEDs, especially in the range of 220-240 nm, for the purpose of disinfecting the environment, but the efficiency of such deep UV-LEDs is highly demanding for mass adoption. Over the last two decades, several research groups have worked out that the optical power of GaN-based LEDs significantly decreases during operation, and with the passage of time, many mechanisms responsible for the degradation of such devices start playing their roles. Only a few attempts, to explore the reliability of these LEDs, have been presented so far which provide very little information on the output power degradation of these LEDs with the passage of time. Therefore, the aim of this review is to summarize the degradation factors of AlGaN-based near UV-LEDs emitting in the range of 200-350 nm by means of combined optical and electrical characterization so that work groups may have an idea of the issues raised to date and to achieve a wavelength range needed for disinfecting the environment from SARS-CoV-2. The performance of devices submitted to different stress conditions has been reviewed for the reliability of AlGaN-based UV-LEDs based on the work of different research groups so far, according to our knowledge. In particular, we review: (1) fabrication strategies to improve the efficiency of UV-LEDs; (2) the intensity of variation under constant current stress for different durations; (3) creation of the defects that cause the degradation of LED performance; (4) effect of degradation on C-V characteristics of such LEDs; (5) I-V behavior variation under stress; (6) different structural schemes to enhance the reliability of LEDs; (7) reliability of LEDs ranging from 220-240 nm; and (8) degradation measurement strategies. Finally, concluding remarks for future research to enhance the reliability of near UV-LEDs is presented. This draft presents a comprehensive review for industry and academic research on the physical properties of an AlGaN near UV-LEDs that are affected by aging to help LED manufacturers and end users to construct and utilize such LEDs effectively and provide the community a better life standard.
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Affiliation(s)
- Mudassar Maraj
- Research Center for Optoelectronic Materials and Devices, Guangxi Key Laboratory for the Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Li Min
- Research Center for Optoelectronic Materials and Devices, Guangxi Key Laboratory for the Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Wenhong Sun
- Research Center for Optoelectronic Materials and Devices, Guangxi Key Laboratory for the Relativistic Astrophysics, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
- MOE Key Laboratory of New Processing Technology for Non-Ferrous Metals and the Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials, Guangxi University, Nanning 530004, China
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Yue Y, Sun M, Li X, Liu T, Lu Y, Chen J, Peng Y, Maraj M, Zhang J, Sun W. Quality improvement mechanism of sputtered AlN films on sapphire substrates with high-miscut-angles along different directions. CrystEngComm 2021. [DOI: 10.1039/d1ce00654a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We studied the annealing mechanism of the films with high-miscut-angles at low cost and high efficiency and revealed the essence of annealing to improve the film quality lies in the annihilation of grain boundaries during the recrystallization.
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Affiliation(s)
- Yang Yue
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Maosong Sun
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Xu Li
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
| | - Ting Liu
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yong Lu
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jie Chen
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Yi Peng
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Mudassar Maraj
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
| | - Jicai Zhang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
- College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Wenhong Sun
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China
- Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
- Guangxi Key Laboratory for Relativistic Astrophysics, School of Physical Science & Technology, Guangxi University, Nanning 530004, China
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Maraj M, Nabi G, Usman K, Wang E, Wei W, Wang Y, Sun W. High Quality Growth of Cobalt Doped GaN Nanowires with Enhanced Ferromagnetic and Optical Response. Materials (Basel) 2020; 13:E3537. [PMID: 32796564 PMCID: PMC7475854 DOI: 10.3390/ma13163537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/04/2020] [Accepted: 08/05/2020] [Indexed: 11/16/2022]
Abstract
Group III-V semiconductors with direct band gaps have become crucial for optoelectronic and microelectronic applications. Exploring these materials for spintronic applications is an important direction for many research groups. In this study, pure and cobalt doped GaN nanowires were grown on the Si substrate by the chemical vapor deposition (CVD) method. Sophisticated characterization techniques such as X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), High-Resolution Transmission Electron Microscopy (HRTEM) and photoluminescence (PL) were used to characterize the structure, morphology, composition and optical properties of the nanowires. The doped nanowires have diameters ranging from 60-200 nm and lengths were found to be in microns. By optimizing the synthesis process, pure, smooth, single crystalline and highly dense nanowires have been grown on the Si substrate which possess better magnetic and optical properties. No any secondary phases were observed even with 8% cobalt doping. The magnetic properties of cobalt doped GaN showed a ferromagnetic response at room temperature. The value of saturation magnetization is found to be increased with increasing doping concentration and magnetic saturation was found to be 792.4 µemu for 8% cobalt doping. It was also depicted that the Co atoms are substituted at Ga sites in the GaN lattice. Furthermore N vacancies are also observed in the Co-doped GaN nanowires which was confirmed by the PL graph exhibiting nitrogen vacancy defects and strain related peaks at 455 nm (blue emission). PL and magnetic properties show their potential applications in spintronics.
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Affiliation(s)
- Mudassar Maraj
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (E.W.); (W.W.); (Y.W.)
- Department of Physics, University of Gujrat, Gujrat 50700, Pakistan
| | - Ghulam Nabi
- Department of Physics, University of Gujrat, Gujrat 50700, Pakistan
| | - Khurram Usman
- International Academy of Optoelectronics, South China Normal University, Zhaoqing 526000, China;
| | - Engui Wang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (E.W.); (W.W.); (Y.W.)
| | - Wenwang Wei
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (E.W.); (W.W.); (Y.W.)
| | - Yukun Wang
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (E.W.); (W.W.); (Y.W.)
| | - Wenhong Sun
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (E.W.); (W.W.); (Y.W.)
- Guangxi Key Laboratory of Processing for Non-Ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
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Maraj M, Wei W, Peng B, Sun W. Dielectric and Energy Storage Properties of Ba (1-x)Ca xZr yTi (1-y)O 3 (BCZT): A Review. Materials (Basel) 2019; 12:ma12213641. [PMID: 31694269 PMCID: PMC6862191 DOI: 10.3390/ma12213641] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 10/31/2019] [Accepted: 10/31/2019] [Indexed: 11/29/2022]
Abstract
The Ba(1−x)CaxZryTi(1−y)O3 (BCZT), a lead-free ceramic material, has attracted the scientific community since 2009 due to its large piezoelectric coefficient and resulting high dielectric permittivity. This perovskite material is a characteristic dielectric material for the pulsed power capacitors industry currently, which in turn leads to devices for effective storage and supply of electric energy. After this remarkable achievement in the area of lead-free piezoelectric ceramics, the researchers are exploring both the bulk as well as thin films of this perovskite material. It is observed that the thin film of this materials have outstandingly high power densities and high energy densities which is suitable for electrochemical supercapacitor applications. From a functional materials point of view this material has also gained attention in multiferroic composite material as the ferroelectric constituent of these composites and has provided extraordinary electric properties. This article presents a review on the relevant scientific advancements that have been made by using the BCZT materials for electric energy storage applications by optimizing its dielectric properties. The article starts with a BCZT introduction and discussion of the need of this material for high energy density capacitors, followed by different synthesis techniques and the effect on dielectric properties of doping different materials in BCZT. The advantages of thin film BCZT material over bulk counterparts are also discussed and its use as one of the constituents of mutiferroic composites is also presented. Finally, it summarizes the future prospects of this material followed by the conclusions.
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Affiliation(s)
- Mudassar Maraj
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (W.W.)
| | - Wenwang Wei
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (W.W.)
| | - Biaolin Peng
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (W.W.)
- Correspondence: (B.P.); (W.S.); Tel.: +86-13878122495 (W.S.)
| | - Wenhong Sun
- Research Center for Optoelectronic Materials and Devices, School of Physical Science and Technology, Guangxi University, Nanning 530004, China; (M.M.); (W.W.)
- Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured Materials, Guangxi University, Nanning 530004, China
- Correspondence: (B.P.); (W.S.); Tel.: +86-13878122495 (W.S.)
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Abstract
BACKGROUND Mammography is the primary method used for breast cancer screening. However, compliance with recommended screening practices is still below acceptable levels. This study examined the cost-effectiveness of five combinations of physician recommendation and telephone or in-person individualized counseling strategies for increasing compliance with mammography. METHODS There were 808 participants who were randomly assigned to one of six groups. A logistic regression model with compliance as the dependent variable and group as the independent variable was used to test for significant differences and a ratio of cost to improvement in mammogram compliance evaluated the cost-effectiveness. RESULTS Three of the interventions (in-person, telephone plus letter, and in-person plus letter) had significantly better compliance rates compared with the control, physician letter, or telephone alone. However, when considering costs, only one emerged as the superior strategy. The cost-effectiveness ratios for the five interventions show that telephone-plus-letter is the most cost-effective strategy, achieving a 35.6% mammography compliance at a marginal cost of $0.78 per 1% increase in women screened. CONCLUSIONS A tailored phone prompt and physician reminder is an effective and economical intervention to increase mammography. Future research should confirm this finding and address its applicability to practice.
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Affiliation(s)
- R M Saywell
- Department of Family Medicine and Bowen Research Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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