CRYSTALLINE PHASE SEPARATION OF InGaN LAYER MATERIALS PREPARED BY METALORGANIC CHEMICAL VAPOR DEPOSITION

2002 ◽  
Vol 16 (01n02) ◽  
pp. 268-274
Author(s):  
ZHE CHUAN FENG ◽  
TZUEN RONG YANG ◽  
RONG LIU ◽  
ANDREW THYE SHEN WEE

Zn -doped InGaN thin films were epitaxied on the top of 1-2 micron thick GaN grown on sapphire by metal organic chemical vapor deposition, and studied by a combination of high resolution X-ray diffraction (HR-XRD), micro-photoluminescence (PL) and secondary ion mass spectrometry (SIMS). HRXRD exhibits a GaN band and a single band from InGaN for samples without phase separation, but two or more InGaN bands corresponding to different x(In) for samples with phase separation. PL emissions from InGaN spread over a wider energy ranges and were modulated by the interference effects. Excitation power dependence measurements reveal 2-sets of PL emissions for samples with phase separation, but only 1-set for samples without phase separation. SIMS data showed that phase separated InGaN:Zn films possess a high Zn concentration near the InGaN-GaN interface and non-uniform distributions of In and Zn contents, which are in contrast with data from InGaN:Zn films with no In -phase separation. These interesting results are correlated to the growth process and microstructural properties.

1992 ◽  
Vol 275 ◽  
Author(s):  
Jiming Zhang ◽  
Robin Gardiner ◽  
Peter S. Kirlin

ABSTRACTYBa2Cu3O7−x thin films have been grown in-situ on Si (100) with a composite buffer layer of Pt/Ta/ONO (ONO stands for a S1O2 / Si3N4 /SiO2 trilayer) by plasma enhanced metal organic chemical vapor deposition (PE-MOCVD). X-ray diffraction measurements indicate that c-axis oriented YBa2Cu3O7−x films are formed in-situ at substrate temperatures as low as 650 °C on Pt/Ta/ONO/Si. The composite P/Ta/ONO provided an adherent metallic interlayer and effectively prevented the interaction between YBa2Cu3O7−x and Si. Four probe resistivity measurements indicate the onset of superconductivity at 92 K and achieved zero resistance at 65 K.


Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1031 ◽  
Author(s):  
Chunyang Jia ◽  
Dae-Woo Jeon ◽  
Jianlong Xu ◽  
Xiaoyan Yi ◽  
Ji-Hyeon Park ◽  
...  

In this work, we have achieved synthesizing large-area high-density β-Ga2O3 nanowires on c-plane sapphire substrate by metal–organic chemical vapor deposition assisted with Au nanocrystal seeds as catalysts. These nanowires exhibit one-dimensional structures with Au nanoparticles on the top of the nanowires with lengths exceeding 6 μm and diameters ranging from ~50 to ~200 nm. The β-Ga2O3 nanowires consist of a single-crystal monoclinic structure, which exhibits strong ( 2 ¯ 01) orientation, confirmed by transmission electronic microscopy and X-ray diffraction analysis. The PL spectrum obtained from these β-Ga2O3 nanowires exhibits strong emissions centered at ~360 and ~410 nm, respectively. The energy band gap of the β-Ga2O3 nanowires is estimated to be ~4.7 eV based on an optical transmission test. A possible mechanism for the growth of β-Ga2O3 nanowires is also presented.


1995 ◽  
Vol 379 ◽  
Author(s):  
R. M. Biefeld ◽  
S. R. Kurtz

ABSTRACTWe have prepared InAsSb/InGaAs strained-layer superlattices (SLS's) and InPSb confinement layers using metal-organic chemical vapor deposition (MOCVD) for use as infrared emitters. X-ray diffraction was used to determine lattice matching as well as composition and structure of the SLS's. Photoluminescence linewidth and intensity were used as a measure of the quality of the structures. Typical FWHM were less than 10 meV. The presence of interface layers were indicated by broadened x-ray diffraction peaks for samples grown under non-optimized conditions. Two types of interfacial layers apparently due to a difference in composition at the interfaces were observed with transmission electron microscopy (TEM). The width of the x-ray peaks can be explained by a variation of the interfacial layer thicknesses. Optimized growth resulted in SLS's with narrow x-ray peaks and high radiative efficiency. Room temperature LEDs operating between 4-5 μm have been prepared.


1999 ◽  
Vol 75 (15) ◽  
pp. 2202-2204 ◽  
Author(s):  
M. K. Behbehani ◽  
E. L. Piner ◽  
S. X. Liu ◽  
N. A. El-Masry ◽  
S. M. Bedair

1992 ◽  
Vol 275 ◽  
Author(s):  
D. L. Schulzi ◽  
B. Hano ◽  
D. Neumayer ◽  
B. J. Hinds ◽  
T. J. Markst ◽  
...  

ABSTRACTThe synthesis of superconducting Tl-Ba-Ca-Cu-O thin films on metal foils (Au and Ag) by metal-organic chemical vapor deposition (MOCVD) has been investigated. Ba-Ca-Cu-O-(F) films are first prepared via MOCVD using fluorinated “second generation” metal-organic precursors. After an intermediate anneal with water vapor-saturated oxygen to promote removal of F, Tl is introduced by annealing in the presence of a mixture of oxides (Tl2O3, BaO, CaO, CuO) of a specific composition. Characterization of the thin films by scanning electron microscopy, EDX, x-ray diffraction, and variable temperature magnetization measurements has been carried out. High temperature superconductor (HTS) films of Tl2Ba2Ca1Cu2O8−x on Au foil exhibit a magnetically derived Tc = 80K and a high degree of texturing with the crystallite c-axes oriented perpendicular to the substrate surface as evidenced by enhanced (000 x-ray diffraction reflections. Thin film coverage on Ag foil becomes non-contiguous during the (Tl2O3, BaO, CaO, CuO) mixture anneal.


2021 ◽  
Vol 15 (6) ◽  
pp. 2170024
Author(s):  
Yuxuan Zhang ◽  
Zhaoying Chen ◽  
Kaitian Zhang ◽  
Zixuan Feng ◽  
Hongping Zhao

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