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Growth of Lattice-Matched InAlN/GaN on Si (111) Substrate for Ultraviolet Photodiode Application
Binh Tinh Tran,Edward Yi Chang 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5
In this paper, we report on the growth of high quality InxAl1-xN/GaN hetero-structures on Si substrate by metal organic chemical vapor deposition with various indium compositions (x = 10.2, 16.2 and 17.6%). The lattice-matched In0.176Al0.838N/GaN structure shows a smooth surface with good crystalline quality. In addition,the ultraviolet photodiode device shows excellent device characteristics with a low leakage current of 0.12 μA,and a high spectral response. It has good quantum efficiency of 94 mA/W and 44% at 265 nm which is comparable to that of the InAlN photodiode grown on sapphire substrate.
Sezawa Guided Mode on Periodic Grooves of GaN/sapphire substrate
Muhammad Musoddiq Jaafar,M. F. Mohd Razip Wee,Chang Fu Dee,Edward Yi Chang,Burhanuddin Yeop Majlis 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.4
Gallium nitride could exhibit strong piezoelectric properties which could be further developed for high frequency devices,telecommunication applications, and many more. In this study, we explored theoretically and experimentally the potentialSezawa guided mode in the groove structure along the GaN/Sapphire interface. Computational analysis with Finite ElementMethod demonstrates the presence three peaks of particular modes at specifics resonance frequencies and interestingly withhigh energy confinement inside the GaN. The experimental data of insertion loss peak graph extrapolated from s-parametermeasurement showed that the results of frequency response are correspond to three peaks of the particular modes hencevalidate the computational results. This finding is attributed to the locally resonant mechanism that confines the energy in theperiodic structure that prevents radiation of energy. This particular propagation can be exploited to enable the developmentof Sezawa-GaN platform to be operational in the liquid medium, for sensor and actuator applications.
Chi-Lang Nguyen,Nguyen Hong Quan,Binh Tinh Tran,Yung-Hsuan Su,Shih-Hsuan Tang,Guang-Li Luo,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4
High crystal quality, smooth surface and fully relaxed Ge1-xSix (0.05 ≤ x ≤ 0.1) buffers are grown on 6°-off (100) Si substrate by UHV-CVD. A low-temperature (LT) Ge seed layer is used to improve the quality of the Ge1-xSix buffers. In this study, the LT-Ge seed layer is deposited directly onto the Si substrate at a low temperature of 315°C. After that, stress-free Si0.1Ge0.9 and Si0.05Ge0.95 layers are grown, respectively. An in-situ annealing process is also performed for the Si0.1Ge0.9/LT-Ge layers to increase the degree of relaxation. The total thickness of the epitaxial layer is 270 nm, with the average surface roughness at 0.6 nm.
Effect of Multiple AlN Layers on Quality of GaN Films Grown on Si Substrates
Binh Tinh Tran,Kung-Liang Lin,Kartika Chandra Sahoo,Chen-Chen Chung,Chi-Lang Nguyen,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.6
In this paper, we present the effect of multiple thin high-low-high-temperature AlN (HLHT AlN) nucleation layers on GaN film quality. A 1.9-μm-thick GaN film grown on Si (111) substrate shows that the multiple HLHT AlN nucleation layers have a significant effect on GaN film quality. This process also plays a very important role in the growth of GaN films on Si (111) substrates. A high quality GaN film with a uniformly faceted surface with very low dislocation densities is obtained at the optimized multiple HLHT AlN nucleation layers 50-nm thick at a temperature of 1010-800-1010°C and a growth pressure of 50 Torr.
Tien-Tung Luong,Binh Tinh Tran,Yen-Teng Ho,Ting-Wei Wei,Yue-Han Wu,Tzu-Chun Yen,Lin-Lung Wei,Jer-Shen Maa,Edward Yi Chang 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.3
The effects of surface pre-treatments and the role of an AlN buffer layer for 2H-SiC growth on c-plane sapphire substrates by thermal CVD are investigated. While the crystallinity of SiC directly grown on sapphire substrate always degrades with a hydrogen pre-treatment but improves by optimizing carbonization, the crystallinity of SiC grown on sapphire substrate using an AlN buffer grown by MOCVD improves with sufficient time of exposure to the H pre-treatment but always deteriorates with carbonization. Detailed microstructural analysis by phi-scan x-ray diffraction reveals that SiC film grown on sapphire substrate consists of crystalline domains with two different crystallographic orientations which are rotated relative to each other along the [111] axis by 60°. A highly oriented hexagonal 2H-SiC film is obtained on low-cost c-plane sapphire substrate by using an AlN buffer. 2H-SiC is unambiguously determined not only by phi-scan x-ray diffraction but also by high-resolution transmission electron microscopy. The growth relationship between 2HSiC and 2H-AlN are coherent due to the favorable bonding of C and Al between SiC and AlN.
The Effect of CdS QDs Structure on the InGaP/GaAs/Ge Triple Junction Solar Cell Efficiency
Chen-Chen Chung,Binh Tinh Tran,Hau-Vei Han,Yen-Teng Ho,Hung-Wei Yu,Kung-Liang Lin,Hong-Quan Nguyen,Peichen Yu,Hao-Chung Kuo,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
This work describes optical and electrical characteristics of InGaP/GaAs/Ge triple-junction (T-J) solar cells with CdS quantum dots (QDs) fabricated by a novel chemical solution. With the anti-reflective feature at long wavelength and down-conversion at UV regime, the CdS quantum dot effectively enhance the overall power conversion efficiency more than that of a traditional GaAs-based device. Experimental results indicate that CdS quantum dot can enhance the short-circuit current by 0.33 mA/cm2, which is observed for the triple-junction solar cells with CdS QDs of about 3.5 nm in diameter. Moreover, the solar cell conversion efficiency is improved from 28.3% to 29.0% under one-sun AM 1.5 global illumination I-V measurement.
Effect of the Circle-Grid Electrodes on Concentrated GaAs Solar Cell Efficiency
Chen-Chen Chung,Binh Tinh Tran,Ming-Hung Han,Kung-Liang Lin,Hung-Wei Yu,Yen-Teng Ho,Chun-Yen Chang,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5
In this study, we investigate the effect of the shading factor of the front grid pattern on concentrated solar cell efficiency, taking the trade-off between the series resistance of the electrodes and the amount of incident light into consideration. We examine the thermal effect with regard to five different circle-grid electrode patterns of the front contact. The front contacts with different grid patterns affect the characteristics of light-concentratedtype GaAs single-junction solar cells. The device parameters analyzed include the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF) and conversion efficiency (η). The results of our study show that for a concentration ratio greater than 60x with AM1.5G, the device with a shading factor of 7.1% has the best cell efficiency of 27.05%, due to the smaller current crowding at the center spot. The results indicate that the conversion efficiency of solar cells can be improved by establishing a compromise between the shading effect and the series resistance effect.