scholarly journals Stable Electron Concentration Si-doped β-Ga2O3 Films Homoepitaxial Growth by MOCVD

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 589
Author(s):  
Teng Jiao ◽  
Zeming Li ◽  
Wei Chen ◽  
Xin Dong ◽  
Zhengda Li ◽  
...  
Keyword(s):  
Electron Concentration ◽  
Defect Density ◽  
Chemical Vapor ◽  
Crystal Quality ◽  
Organic Chemical ◽  
Power Devices ◽  
Homoepitaxial Growth ◽  
Metal Organic ◽  
Si Doped ◽  
Organic Chemical Vapor Deposition

To obtain high-quality n-type doped β-Ga2O3 films, silane was used as an n-type dopant to grow Si-doped β-Ga2O3 films on (100) β-Ga2O3 substrates by metal-organic chemical vapor deposition (MOCVD). The electron concentrations of the Si-doped β-Ga2O3 films obtained through experiments can be stably controlled in the range of 6.5 × 1016 cm−3 to 2.6 × 1019 cm−3, and the ionization energy of Si donors is about 30 meV, as determined by analysis and calculation. The full width at half maxima of the rocking curves of the (400) crystal plane of all doped films was less than 500 arcsec, thus showing high crystal quality, while the increase of the doping concentration increased the defect density in the β-Ga2O3 films, which had an adverse effect on the crystal quality and surface morphology of the films. Compared with heteroepitaxial Si-doped β-Ga2O3 films, homoepitaxial Si-doped β-Ga2O3 films exhibited higher quality, lower defect density, and more stable electron concentration, which make them more conductive for preparing Ga2O3-based power devices.

scholarly journals Highly Conductive n-Al0.65Ga0.35N Grown by MOCVD Using Low V/III Ratio

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1006
Author(s):  
Christian J. Zollner ◽  
Yifan Yao ◽  
Michael Wang ◽  
Feng Wu ◽  
Michael Iza ◽  
...  
Keyword(s):  
Electron Concentration ◽  
Ohmic Contacts ◽  
Chemical Vapor ◽  
Growth Conditions ◽  
Organic Chemical ◽  
Operating Voltage ◽  
Metal Organic ◽  
Silicon Doped ◽  
Uv Leds ◽  
Organic Chemical Vapor Deposition

Highly conductive silicon-doped AlGaN and ohmic contacts are needed for deep-UV LEDs and ultrawide bandgap electronics. We demonstrate improved n-Al0.65Ga0.35N films grown by metal–organic chemical vapor deposition (MOCVD) on sapphire substrates using a low V/III ratio (V/III = 10). A reduced V/III ratio improves repeatability and uniformity by allowing a wider range of silicon precursor flow conditions. AlxGa1−xN:Si with x > 0.5 typically has an electron concentration vs. silicon concentration trend that peaks at a particular “knee” value before dropping sharply as [Si] continues to increase (self-compensation). The Al0.65Ga0.35N:Si grown under the lowest V/III conditions in this study does not show the typical knee behavior, and instead, it has a flat electron concentration trend for [Si] > 3 × 1019 cm−3. Resistivities as low as 4 mΩ-cm were achieved, with corresponding electron mobility of 40 cm2/Vs. AFM and TEM confirm that surface morphology and dislocation density are not degraded by these growth conditions. Furthermore, we report vanadium-based ohmic contacts with a resistivity of 7 × 10−5 Ω-cm2 to AlGaN films grown using a low V/III ratio. Lastly, we use these highly conductive silicon-doped layers to demonstrate a 284 nm UV LED with an operating voltage of 7.99 V at 20 A/cm2, with peak EQE and WPE of 3.5% and 2.7%, respectively.

Intersubband Transitions in GaN/AlxGa1-xN Multi Quantum Wells

2004 ◽  
Vol 829 ◽  
Author(s):  
E. A. DeCuir ◽  
Y. C. Chua ◽  
B. S. Passmore ◽  
J. Liang ◽  
M. O. Manasreh ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Chemical Vapor ◽  
Charge Carriers ◽  
Organic Chemical ◽  
Multiple Quantum ◽  
Intersubband Transitions ◽  
Metal Organic ◽  
Si Doped ◽  
Organic Chemical Vapor Deposition ◽  
Absorption Technique

ABSTRACTIntersubband transitions (ISTs) in GaN/AlxGa1-xN multiple quantum wells (MQWs) were investigated using an optical absorption technique. Several samples were grown by either Molecular Beam Epitaxy (MBE) or Metal-Organic Chemical Vapor Deposition (MOCVD) and were investigated using both normal incident and waveguide configurations. The waveguides were fabricated by dicing each sample into 2 mm wide by 5 mm long pieces with two facets polished at 45 degrees with respect to the surface such that light propagates across the sample's width. Preliminary results indicate that ISTs are observable in Si-doped and undoped GaN/AlxGa1-xN MQWs. The source of these charge carriers in the undoped samples are explained as being due to the spontaneous polarization effect which exists at the GaN/AlxGa1-xN interfaces where the GaN surface has Ga-polarity. Scanning Electron Microscopy indicates that a sample containing what appeared to be a large number of cracks and or hexagonal voids lacked the presence of ISTs.

Study of Depth-Dependent Tetragonal Distortion of GaN Epilayer with Tri-Layer AlGaN Interlayer Growth on Si(111)

2011 ◽  
Vol 413 ◽  
pp. 11-17 ◽  
Author(s):  
Bin Feng Ding ◽  
Yong Quan Chai
Keyword(s):  
Chemical Vapor ◽  
Crystal Quality ◽  
Tetragonal Distortion ◽  
Organic Chemical ◽  
X Ray Diffraction ◽  
Near Surface ◽  
X Ray ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

A GaN epilayer with tri-layer AlGaN interlayer grown on Si (111) by metal-organic chemical vapor deposition (MOCVD) method was discussed by synchrotron radiation x-ray diffraction (SRXRD) and Rutherford backscattering (RBS)/C. The crystal quality of the epilayer is very good with a χmin=2.1%. According to the results of the θ-2θ scan of GaN(0002) and GaN(1122), the epilayer elastic strains in perpendicular and parallel directions were calculated respectively to be-0.019% and 0.063%. By the angular scan using RBS/C around a symmetric [0001] axis and an asymmetric [1213] axis in the (1010) plane of the GaN layer, the tetragonal distortion (eT ) were determined to be 0.09%. This result coincides with that from SRXRD perfectly. The strain decreases gradually towards the near-surface layer, which will avoid the film cracks efficiently and improve the crystal quality of the GaN epilayer remarkably.

scholarly journals InGaN-Based microLED Devices Approaching 1% EQE with Red 609 nm Electroluminescence on Semi-Relaxed Substrates

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1364
Author(s):  
Ryan C. White ◽  
Hongjian Li ◽  
Michel Khoury ◽  
Cheyenne Lynsky ◽  
Michael Iza ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Defect Density ◽  
Chemical Vapor ◽  
Base Layer ◽  
Organic Chemical ◽  
Material System ◽  
Higher Power ◽  
Metal Organic ◽  
Atomic Probe ◽  
Organic Chemical Vapor Deposition

In this paper, we report the successful demonstration of bright InGaN-based microLED devices emitting in the red spectral regime grown by metal organic chemical vapor deposition (MOCVD) on c-plane semi-relaxed InGaN substrates on sapphire. Through application of an InGaN/GaN base layer scheme to ameliorate high defect density and maintain appropriate lattice constant throughout the growth, high-In quantum wells (QWs) can be grown with improved crystal quality. Improvement to the design of the growth scheme also yields higher power output resulting in an increase to the external quantum efficiency (EQE). Combined, these two improvements allow for an 80 × 80 μm2 microLED device emitting at 609 nm to achieve 0.83% EQE. Furthermore, the true In content of the QW is measured using atomic probe tomography (APT) to confirm the improved In incorporation during high temperature active region growth. These developments represent advancement toward the realization of bright, highly efficient red III-nitride LEDs to be used in RGB applications under one material system.

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