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Low resistive InGaN film grown by metalorganic chemical vapor deposition
(2020-01-01)
Shrestha, Niraj Man
;
Chauhan, Prerna
;
Wong, Yuen-Yee
;
Li, Yiming
;
Samukawa, Seiji
Indium gallium nitride (InGaN) samples were grown on sapphire substrate with low temperature GaN buffer by metalorganic chemical vapor deposition (MOCVD) under varying growth conditions, such as temperature, pressure and ammonia flow. Although high indium composition is considered as indispensable parameter for sheet carrier concentration (n(s)) and low sheet resistance (R-s), our outcomes disclose that higher indium composition in InGaN film doesn't always have high n(s) and low R-s. Acceptor nature of carbon related defects, a major trapping sites for electrons, plays a crucial role to limit the carrier concentrations in the InGaN specially grown at low pressure, low temperature and low ammonia flow. Furthermore, study of metal contacts deposited on the grown samples by transmission line method (TLM) shows that carrier concentration is the most important factor to obtain low contact resistance. The measured contact resistance for the sample with 4.5x 10(16) cm(2) carrier concentration is 0.13 Omm which is among the lowest contact resistance for GaN based materials grown by MOCVD. This proves that the use of InGaN in source and drain contact region can surpassingly reduce contact resistance and significantly improve device performance of AlGaN/GaN device.
Crystal phase control in self-catalyzed InSb nanowires using basic growth parameter V/III ratio
(2019-09-15)
Anandan, Deepak
;
Nagarajan, Venkatesan
;
Kakkerla, Ramesh Kumar
;
Yu, Hung Wei
;
Ko, Hua Lun
In this work, the influence of V/III ratio on self-catalyzed InSb nanowire (NW) crystal structure is investigated using metal organic chemical vapor deposition. The effective balance of V/III ratio determines the change of InSb NW crystal structure from zincblende to wurtzite. Particularly, as group-V molar flow varies from 6.4 x 10(-5) to 8.0 x 10(-5) mol/min, wurtzite segment length of InSb NW increases from 16 +/- 9 nm to 89 +/- 9 nm, whereas zincblende crystal phase is observed for other molar flows. We interpret the observed phase transition to a lower surface energy of In-Sb alloy droplet than pure In-droplet, which makes triple phase line nucleation energetically favorable. This study gives insight on single growth parameter (V/III ratio) change to the InSb NW crystal control, such a technique is essential to selectively tune the crystal phase of single NW for various applications.
Enhancing the Emission Efficiency of In0.2Ga0.8N/GaN MQW Blue LED by Using Appropriately Misoriented Sapphire Substrates
(2009-01-01)
Li, Zhen-Yu
;
Uen, Wu-Yih
;
Lo, Ming-Hua
;
Chiu, Ching-Hua
;
Lin, Po-Chun
In this paper, we report the fabrication of an In0.2Ga0.8N/GaN multiple-quantum-well (MQW) structure on vicinal sapphire substrates with a very small offset angle of 0-1 degrees by low-pressure metallorganic chemical vapor deposition. Our study demonstrates that the quality of the In0.2Ga0.8N/GaN MQW structure is very sensitive to the offset angle of the vicinal substrate. High-resolution X-ray diffraction analyses demonstrated high-order satellite peaks and clear fringes between them for all MQW structures fabricated, from which the interface roughness (IRN) was estimated. The IRN of the In0.2Ga0.8N/GaN MQW structure fabricated on 0.2 degrees off sapphire substrate was determined as 1.36% of the quantum well layer period. Besides, reciprocal lattice mapping was employed to examine the strain status of the MQW. The lattice relaxation of the same specimen mentioned above was estimated to be 7.4x10(-5). It is therefore manifested that an In0.2Ga0.8N/GaN MQW structure with abrupt interfaces and good layer periodicity was grown. From it, a shortest radiative lifetime of 14.2 ns and a lowest fluctuation of 5.6 meV in the emission energy of micro-photoluminescence mapping were achieved. In addition, superior material qualities of the whole film fabricated on 0.2 degrees off substrate were recognized by cross-sectional transmission electron microscopy. Based on the results mentioned above, a high-quality In0.2Ga0.8N/GaN MQW blue light, emitting diode (LED) has been fabricated on 0.2 degrees off substrate, which demonstrated a strong room-temperature electroluminescence emission at the wavelength of 465 nm and with the full width at half maximum of only 19 nm. The same device also showed an output power of 13.4 mW and an external quantum efficiency of 19.2%. Both these characteristics are improved drastically compared with the devices fabricated on the substrates with other offset angles. Conclusively, the use of an appropriately misoriented sapphire substrate is suggested to be effective for elevating the emission efficiency of In0.2Ga0.8N/GaN MQW blue LED fabricated thereon.
Effect of N-2/H-2 plasma treatment on the moisture adsorption of MOCVD-TiN films
(2011-05-31)
Huang, J. K.
;
Huang, Cheng-Liang
;
Chang, Shih-Chieh
;
Cheng, Yi-Lung
;
Wang, Ying-Lang
In the application of contact glue layer for semiconductor devices, a nitrogen/hydrogen (N-2/H-2) plasma treatment is usually used to reduce the amount of C and O impurities of metallorganic chemical vapor deposition titanium nitride (MOCVD-TiN) films. This study found that the sheet resistance of as-deposited MOCVD-TiN film without N-2/H-2 plasma treatment dramatically increased with exposure time due to moisture adsorption. Increasing plasma treatment power and time was able to retard the increase in sheet resistance. From residue gas analysis at 200 degrees C, it was found that the amount of H2O outgases from the MOCVD-TiN films decreased with increasing plasma treatment power and time. TEM images reveal that the surface of the MOCVD-TiN films became compact as it received more plasma treatment energy, making it difficult for the external moisture to diffuse into and react with the MOCVD-TiN films. (C) 2011 Elsevier B.V. All rights reserved.
Growth of foreign-catalyst-free vertical InAs/InSb heterostructure nanowires on Si (111) substrate by MOCVD
(2019-01-15)
Anandan, Deepak
;
Kakkerla, Ramesh Kumar
;
Yu, Hung Wei
;
Ko, Hua Lun
;
Nagarajan, Venkatesan
In this study, growth of Au-free InAs/InSb vertical heterostructure (HS) nanowires (NWs) on highly lattice mismatched Si (1 1 1) substrate by metal organic chemical vapor deposition (MOCVD) is demonstrated. Careful selections of InSb growth parameters lead to In-rich growth regime such that direct impingement of growth precursors on top of grown InAs NW (self-assembled) stems result in axial InSb HSs nucleation on InAs stems. The observed indium (In) droplet on InSb HS NW tip shows that InSb HS growth followed a self-catalyzed growth mechanism. InSb HS axial growth rate and morphology are controlled by growth temperature and growth time. A small change in the growth parameters significantly affects In particle accumulation, particle size and its chemical composition, and thus affects the InSb nucleation on the stem. Especially, it is found that (i) growth time of less 10 min yields vertical InSb HS NW on the top of the InAs stem, (ii) as the growth time increases above 10 min, the growth turned to be InSb wrapped InAs/InSb core-shell HS due to coaxial lateral growth. High resolution transmission electron microscopy (HRTEM) study reveals that all the InSb HSs exhibit pure zinc-blende (ZB) crystal structure. The results presented here provide significant guidelines for external catalyst-free InAs/InSb HS NW growth using MOCVD on silicon (Si) substrate for various optoelectronics and electronics applications.
Enhanced metalorganic chemical vapor deposition titanium nitride film fabricated using tetrakis-dimethylamino-titanium for barrier metal application in sub-half-micron technology
(1996-08-01)
Wang, CK
;
Liu, LM
;
Liao, M
;
Cheng, HC
;
Lin, MS
Enhanced metalorganic chemical vapor deposition (MOCVD) titanium nitride (TiN:C) film with low resistivity (< 700 mu Omega . cm) has been fabricated by thermal decomposition of tetrakis-dimethylamino-titanium (TDMAT; Ti[N(CH3)(2)](4)) Enhancement is carried out by in-situ N-2 plasma treatment of as-deposited TiN:C film and the enhanced TiN:C film has good stability: less than 4% increase in film resistivity after exposure to air for 24 days. The amount of oxygen absorbed in this enhanced TiN:C film after air exposure, determined by Auger electron spectroscopy (AES) was significantly reduced. This enhanced MOCVD TiN:C film has been successfully applied to sub-half-micron devices. A void-tree tungsten plug (W plug) for sub-half-micron holes can be achieved. Good barrier performance and low contact/via resistance have also been demonstrated.
Effects of growth temperature on solid incorporation of AlAs1-xSbx using tertiarybutylarsine as arsenic source precursor
(1996-10-01)
Chen, WK
;
Ou, JH
;
Hsu, CH
;
電子物理學系
;
Department of Electrophysics
We have investigated the effects of growth temperature on the solid incorporation of AlAsSb epilayers grown LJ metalorganic vapor-phase epitaxy using TMAl, TBAs and TMSb as source precursors. The solid incorporation of AlAsSb was found to be strongly affected by the pyrolysis reactions and kinetics of the source precursors, in particular, TMAl and TBAs. Our experimental results indicated that the, Al incorporation efficiency increases with the growth temperature and saturates at temperatures above similar to 625 degrees C. On the other hand, the growth behavior of As is anomalous: the As incorporation efficiency increases initially with growth temperature, and decreases monotonously at temperatures above similar to 550 degrees C. The reduced As incorporation efficiency at high temperatures may be closely related to the beta-elimination process of TBAs, and to the formation of adducts in the gas phase.
Demonstrating antiphase domain boundary-free GaAs buffer layer on zero off-cut Si (001) substrate for interfacial misfit dislocation GaSb film by metalorganic chemical vapor deposition
(2017-08-01)
Minh Thien Huu Ha
;
Sa Hoang Huynh
;
Huy Binh Do
;
Tuan Anh Nguyen
;
Quang Ho Luc
High quality 40 nm GaSb thin film was grown on the zero off-cut Si (001)-oriented substrate using metalorganic chemical vapor deposition with the temperature-graded GaAs buffer layer. The growth time of the GaAs nucleation layer, which was deposited at a low temperature of 490 degrees C, is systematically investigated in this paper. Cross-sections of the high resolution transmission electron microscopy images indicate that the GaAs compound formed 3D-islands first before to quasi-2D islands, and finally formed uniform GaAs layer. The optimum thickness of the 490 degrees C-GaAs layer was found to be 10 nm to suppress the formation of antiphase domain boundaries (APDs). The thin GaAs nucleation layer had a root-mean-square surface roughness of 0.483 nm. This allows the continued high temperature GaAs buffer layer to be achieved with low threading dislocation density of around 7.1 x 10(6) cm(-2) and almost invisible APDs. Finally, a fully relaxed GaSb film was grown on the top of the GaAs/Si heterostructure using interfacial misfit dislocation growth mode. These results indicate that the GaSb epitaxial layer can be grown on Si substrate with GaAs buffer layer for future p-channel metal-oxide-semiconductor field effect transistors (MOSFETs) applications.
Investigations of GaN growth on the sapphire substrate by MOCVD method with different AlN buffer deposition temperatures
(2016-04)
Huang, Wei-Ching
;
Chu, Chung-Ming
;
Wong, Yuen Yee
;
Chen, Kai-Wei
;
Lin, Yen-Ku
The effects of different AlN buffer deposition temperatures on the GaN material properties grown on sapphire substrate was investigated. At relatively higher AlN buffer growth temperature, the surface morphology of subsequent grown GaN layer was decorated with island-like structure and revealed the mixed-polarity characteristics. In addition, the density of screw TD and leakage current in the GaN film was also increased. The occurrence of mixed-polarity GaN material result could be from unintentional nitridation of the sapphire substrate by ammonia (NH3) precursor at the beginning of the AlN buffer layer growth. By using two-step temperature growth process for the buffer layer, the unintentional nitridation could be effectively suppressed. The GaN film grown on this buffer layer exhibited a smooth surface, single polarity, high crystalline quality and high resistivity. AlGaN/GaN high electron-mobility transistor (HEMT) devices were also successfully fabricated by using the two-step AlN buffer layer. (C) 2016 Elsevier Ltd. All rights reserved.
Study on GaN micro-rod growth by nature patterned sapphire substrate
(2009)
Hsu, S. C.
;
Tu, P. M.
;
Chen, I. R.
;
Cheng, Y. J.
;
光電工程學系
In this study, we Investigated the kinetics and etched morphology on sapphire substrate by mixing acid solutions We developed different etching conditions to produce various etching morphology patterns on sapphire surface Then, GaN micro-rod embedded with quantum wells (QWs) were grown on the patterned sapphire surface The cathode luminescence (CL) images of these QW embedded micro-rods have shown great crystal quality.

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