Browsing by Author "Hong-Quan Nguyen"

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Characterizations of GaN Films Grown on Si (111) Substrates with Various Growth Temperatures of Multiple AlN Buffer Layers
(2012)
Binh-Tinh Tran
;
Chang, Edward Yi
;
Lin, Kung-Liang
;
Luong, Tien-Tung
;
Yu, Hung-Wei
We present the effect of multiple AlN buffer layers on characterizations of GaN film quality, which includes a thin high-low-high-temperature (HLHT) AlN buffer layers. The study is based on two different thicknesses of the GaN films on the buffers and found that the HLHT AlN buffer layers could significantly affect on the GaN films qualities. The buffer plays a very important role for the growth of GaN film on Si (111) substrate. The GaN film with an uniformly faceted surface and very high-quality has been obtained at the optimized multiple HLHT AlN buffer layers of 50-nm-thick at 1010-800-1010 degrees C.
Demonstrating 1 nm-oxide-equivalent-thickness HfO2/InSb structure with unpinning Fermi level and low gate leakage current density
(2013-09-30)
Hai-Dang Trinh
;
Lin, Yueh-Chin
;
Minh-Thuy Nguyen
;
Hong-Quan Nguyen
;
Quoc-Van Duong
In this work, the band alignment, interface, and electrical characteristics of HfO2/InSb metaloxide-semiconductor structure have been investigated. By using x-ray photoelectron spectroscopy analysis, the conduction band offset of 1.78 +/- 0.1 eV and valence band offset of 3.35 +/- 0.1 eV have been extracted. The transmission electron microscopy analysis has shown that HfO2 layer would be a good diffusion barrier for InSb. As a result, 1 nm equivalent-oxide-thickness in the 4 nm HfO2/InSb structure has been demonstrated with unpinning Fermi level and low leakage current of 10(-4) A/cm(-2). The D-it value of smaller than 10(12) eV(-1) cm(-2) has been obtained using conduction method. (C) 2013 AIP Publishing LLC.
Effect of annealing processes on the electrical properties of the atomic layer deposition Al2O3/In0.53Ga0.47As metal oxide semiconductor capacitors
(2014-04-01)
Quang-Ho Luc
;
Chang, Edward Yi
;
Trinh, Hai-Dang
;
Hong-Quan Nguyen
;
Binh-Tinh Tran
The influence of different annealing processes including post deposition annealing (PDA) and post metallization annealing (PMA) with various temperatures (250-400 degrees C) and ambient [N-2 and forming gas (FG)] on the electrical characteristics of Pt/Al2O3/In0.53Ga0.47As MOSCAPs are systemically studied. Comparing to samples underwent high PDA temperature, the higher leakage current has been observed for all of samples underwent high PMA temperature. This has resulted in the degradation of capacitance-voltage (C-V) behaviors. In conjunction with the current-voltage (J-V) measurement, depth profiling Auger electron spectroscopy (AES) and high-resolution transmission electron microscopy (HRTEM) analyses evidence that the out-diffusion of metal into oxide layer is the main source of leakage current. The noticeable passivation effect on the Al2O3/InGaAs interface has also been confirmed by the samples that underwent PDA process. (C) 2014 The Japan Society of Applied Physics
Effect of Different Tunnel diodes on The Efficiency of Multi-junction III-V Solar cells
(2014-01-01)
Yu, Hung-Wei
;
Hong-Quan Nguyen
;
Chung, Chen-Chen
;
Hsu, Ching-Hsiang
;
Hsiao, Chih-Jen
InGaP/GaAs dual-junction solar cells with different tunnel diodes (TDs) grown on misoriented GaAs substrates are investigated. It is found that the solar cells with P++-AlGaAs/N++-GaAs TDs grown on 10 degrees off GaAs substrates show a higher external quantum efficiency (EQE) but also generate a higher peak current density (J(peak)) than the solar cells with P++-GaAs/N++-InGaP TDs grown on 10 degrees off GaAs substrates. Furthermore, smooth surface (rms roughness: 1.54 angstrom) and sharp interface for the GaAs/Al0.3Ga0.7As TDs were obtained when the (100) tilted 10 degrees off toward [111] GaAs substrate was used. The conversion efficiency of InGaP/GaAs dual-junction solar cell with N++-GaAs/P++-AlGaAs TD grown on the (100) tilted 10 degrees off toward (111) GaAs substrate is close to 20%.
Formation of a Multi-Arm Branched Nanorod of ZnO on the Si Surface via a Nanoseed-Induced Polytypic Crystal Growth Using the Hydrothermal Method
(2013-07-01)
Tan, Sin Tee
;
Umar, Akrajas Ali
;
Yahaya, Muhammad
;
Salleh, Muhamad Mat
;
Yap, Chi Chin
A branched nanorod of ZnO composed of multiple branches that projects from a single nanorod backbone can be realized by using a hydrothermal approach in the presence of a nanoseed with a special structure, namely multi-faceted orthorhombic Zn2SiO4. Orthorhombic Zn2SiO4 was prepared by annealing the ZnO nanoseed of size ca. 15 nnn on a Si substrate at a temperature of 900 degrees C in air for one hour. A typical branched nanorod was constructed by a hexagonal-and rectangular-shaped nanorod arm. HRTEM analysis on the branched structure indicated that the branches exhibited a different crystal growth direction [002] and [100], reflecting the presence of a polytypic growth process in the formation of the branched nanorod structure. The branched nanorod of ZnO and its feature-rich faceted property appears promising for solar cell, catalytic and sensing applications.
Gold-Free Cu-Metallized III-V Solar Cell
(2014-01-01)
Hsu, Ching-Hsiang
;
Chang, Hsun-Jui
;
Yu, Hung-Wei
;
Hong-Quan Nguyen
;
Ma, Jer-Shen
-Au-free, fully Cu-metallized InGaP/InGaAs/Ge triple-junction solar cells using Pd/Ge/Cu as front contact and Pt/Ti/Pt/Cu/Cr as back contact were fabricated and the results are reported for the first time. From the specific contact resistance measurement, these Cu-metallized ohmic contacts have low contact resistance in the order of 10(-6) Omega-cm(2). AES and TEM results clearly show the formation mechanisms of the Cu-metallization ohmic structures, for Pd/Ge/Cu contact, it was due to the formation of Ge diffusion into the GaAs layer, and for the Pt/Ti/Pt/Cu/Cr contact, it was due to high work function of Pt layer, these copper metallized ohmic contacts were quite stable even after 310 degrees C annealing. The I-V curves of the Cu-metallized InGaP/InGaAs/Ge triple-junction solar cells showed similar electrical characteristics to the solar cells with Au-metallized triple junction solar cell. Overall, the Pd/Ge/Cu and Pt/Ti/Pt/Cu ohmic contacts have been successfully applied to the InGaP/InGaAs/Ge triple-junction solar cells and demonstrated excellent performance.
Growth of High-Quality In(0.4)Ga(0.6)N Film on Si Substrate by Metal Organic Chemical Vapor Deposition
(2011-11-01)
Binh-Tinh Tran
;
Chang, Edward-Yi
;
Lin, Kung-Liang
;
Wong, Yuen-Yee
;
Sahoo, Kartika Chandra
High-quality In(0.4)Ga(0.6)N film grown on GaN/AlN/Si(111) templates was obtained by metal organic chemical vapor deposition (MOCVD) with negligible phase separation. A template of high-quality GaN grown on a Si(111) substrate using AlN buffer layers was used for subsequent In(0.4)Ga(0.6)N growth. The GaN layer was 0.6 mu m thick with rocking-curve full width at half maximum (FWHM) for a GaN(002) peak better than 430 arcsec. The In(0.4)Ga(0.6)N film grown was 0.3 mu m thick with a dislocation density of 6 x 10(7) cm(-2) and X-ray (omega-2 theta) FWHM better than 130 arcsec. (C) 2011 The Japan Society of Applied Physics
Growth of High-Quality In0.4Ga0.6N Film on Si Substrate by Metal Organic Chemical Vapor Deposition
(2011-11-01)
Binh-Tinh Tran
;
Chang, Edward-Yi
;
Lin, Kung-Liang
;
Wong, Yuen-Yee
;
Sahoo, Kartika Chandra
High-quality In0.4Ga0.6N film grown on GaN/AlN/Si(111) templates was obtained by metal organic chemical vapor deposition (MOCVD) with negligible phase separation. A template of high-quality GaN grown on a Si(111) substrate using AlN buffer layers was used for subsequent In0.4Ga0.6N growth. The GaN layer was 0.6 mu m thick with rocking-curve full width at half maximum (FWHM) for a GaN(002) peak better than 430 arcsec. The In0.4Ga0.6N film grown was 0.3 mu m thick with a dislocation density of 6 x 10(7) cm(-2) and X-ray (omega-2 theta) FWHM better than 130 arcsec. (C) 2011 The Japan Society of Applied Physics
Influence of post deposition annealing temperatures on electrical properties of Al2O3/InSb MOSCAPs
(2012-01-01)
Hai-Dang Trinh
;
Lin, Yue-Chin
;
Chang, Edward Yi
;
Hong-Quan Nguyen
;
Wang, Shin-Yuan
The influence of post deposition annealing (PDA) temperatures on electrical characteristics of Al2O3/InSb metal-oxide-semiconductor capacitor (MOSCAP) structures is investigated. Low frequency C-V responses with strong inversion behavior in the whole range of measured frequency (100 Hz-1 MHz) are observed, indicating very short minority carrier response time in InSb. The PDA temperature of 300 degrees C and above would result in the reduction of maximum capacitance. At the PDA temperature of above 300 degrees C the C-V hysteresis, frequency dispersion and stretch out increases significantly, indicating the degradation of the MOSCAP structures. The degradation might relate to the interdiffusion between Al2O3 and InSb during thermal steps.
Investigation of Characteristics of Al2O3/n-In (x) Ga1-x As (x=0.53, 0.7, and 1) Metal-Oxide-Semiconductor Structures
(2013-08-01)
Trinh, Hai-Dang
;
Lin, Yueh-Chin
;
Kuo, Chien-I
;
Chang, Edward Yi
;
Hong-Quan Nguyen
The electrical properties of Al2O3/n-InGaAs metal-oxide-semiconductor capacitors (MOSCAPs) with In content of 0.53, 0.7, and 1 (InAs) have been investigated. Results show small capacitance-voltage (C-V) frequency dispersion in accumulation (1.70% to 1.85% per decade) for these MOSCAPs, mostly being assigned to border traps in Al2O3. With higher In content, shorter minority-carrier response time and smaller C-V hysteresis are observed. The reduction of C-V hysteresis might be related to the reduction of Ga-bearing oxides in Al2O3/InGaAs interfaces as indicated by x-ray photoelectron spectroscopy.
Performance improvement of highly mismatched GaSb layers on GaAs by interfacial-treatment-assisted chemical vapor deposition
(2017-01)
Hsiao, Chih-Jen
;
Minh-Thien-Huu Ha
;
Liu, Chun-Kuan
;
Hong-Quan Nguyen
;
Yu, Hung-Wei
Strain-relieved GaSb quantum dots on GaAs can be achieved by either periodic interfacial misfit (IMF) or the conventional Stranski-Krastanov (SK) growth modes by changing the growth parameters. In this study, the Sb interfacial treatment was employed to improve the GaSb crystal quality including low defect density, smooth surface morphology, and high hole mobility. This technique yields two-dimensional (2D) islands with a height as low as 1.7 nm and width up to 190 nm in the IMF growth mode. In contrast to the interfacial treatments conventionally employed in the initial strain relaxation of GaSb/GaAs hererostructure, the Sb treatment promotes the formation of strong Ga-Sb bonds on the surface of the grown island, which effectively reduces the interfacial free energy and thus promotes the formation of 2D islands. With the Sb interfacial treatment, a high-relaxation 100-nm GaSb epilayer was grown on the GaAs substrate, the epilayers was strain relaxed and exhibited enhanced electrical properties with a high hole mobility of similar to 667 cm(2) V-1 s(-1) and with superior optical properties as evidenced by the photoluminescence B-line peak. The results of this study demonstrate an effective interfacial-treatment growth technique to relax the initial strain for the highly mismatched GaSb layers grown on a GaAs substrate.
Structure deformation of indium oxide from nanoparticles into nanostructured polycrystalline films by in situ thermal radiation treatment
(2013-10-17)
Chong, Su Kong
;
Azizan, Siti Nur Azieani
;
Chan, Kee Wah
;
Hong-Quan Nguyen
;
Chiu, Wee Siong
A microstructure deformation of indium oxide (In2O3) nanoparticles by an in situ thermal radiation treatment in nitrous oxide plasma was investigated. The In2O3 nanoparticles were completely transformed into nanostructured In2O3 films upon 10 min of treatment time. The treated In2O3 nanoparticle sample showed improvement in crystallinity while maintaining a large surface area of nanostructure morphology. The direct transition optical absorption at higher photon energy and the electrical conductivity of the In2O3 nanoparticles were significantly enhanced by the treatment.
Threading Dislocation Blocking in Metamorphic InGaAs/GaAs for Growing High-Quality In0.5Ga0.5As and In0.3Ga0.7As on GaAs Substrate by Using Metal Organic Chemical Vapor Deposition
(2012-05-01)
Hong-Quan Nguyen
;
Chang, Edward Yi
;
Yu, Hung-Wei
;
Hai-Dang Trinh
;
Dee, Chang-Fu
High quality In0.3Ga0.7As and In0.51Ga0.49As epilayers have been successfully grown on the GaAs substrate by MOCVD. A cross-sectional study by transmission electron microscopy showed that the threading dislocations (TDs) have been successfully contained and limited within the buffer layers designed to stop the elongation of TDs into the In0.3Ga0.7As and In0.51Ga0.49As epilayers. A TD density of 1 x 10(6) cm(-2) in a fully relaxed In0.51Ga0.49As epilayer was achieved. The measurement of lifetimes of n- and p-type In0.51Ga0.49As has been done by using time-resolved photoluminescence. A great reduction in the number of recombination centers in the InGaAs epilayer has been shown. (c) 2012 The Japan Society of Applied Physics