Growth of Crack-Free Thick AlGaN Layer and its Application to GaN-Based Laser Diode

1999 ◽  
Vol 595 ◽  
Author(s):  
I. Akasaki ◽  
S. Kamiyama ◽  
T. Detchprohm ◽  
T. Takeuchi ◽  
H. Amano
Keyword(s):  
Buffer Layer ◽  
Laser Diode ◽  
Lattice Mismatch ◽  
Molar Fraction ◽  
Vertical Direction ◽  
Thick Layer ◽  
Group Iii Nitrides ◽  
Alloy Layer ◽  
Field Pattern ◽  
Group Iii

AbstractIn the field of group-III nitrides, hetero-epitaxial growth has been one of the most important key technologies. A thick layer of AlGaN alloy with higher AlN molar fraction is difficult to grow on sapphire substrate, because the alloy layer is easily cracked. It is thought that one cause of generating cracks is a large lattice mismatch between an AlGaN and a GaN, when AlGaN is grown on the underlying GaN layer. We have achieved crack-free Al0.07Ga0.93N layer with the thickness of more than 1mm using underlying Al0.05Ga0.95N layer. The underlying Al0.05Ga0.95N layer was grown directly on sapphire by using the lowtemperature-deposited buffer layer (LT-buffer layer). Since a lattice mismatch between the underlying Al0.05Ga0.95N layer and upper Al0.07Ga0.93N layer is relatively small, the generation of cracks is thought to be suppressed. This technology is applied to a GaN-based laser diode structure, in which thick n-Al0.07Ga0.93N cladding layer grown on the Al0.05Ga0.95N layer, improves optical confinement and single-robe far field pattern in vertical direction.

scholarly journals Growth of Crack-Free thick AlGaN Layer and its Application to GaN-Based Laser Diode

2000 ◽  
Vol 5 (S1) ◽  
pp. 452-458
Author(s):  
I. Akasaki ◽  
S. Kamiyama ◽  
T. Detchprohm ◽  
T. Takeuchi ◽  
H. Amano
Keyword(s):  
Buffer Layer ◽  
Laser Diode ◽  
Lattice Mismatch ◽  
Molar Fraction ◽  
Vertical Direction ◽  
Thick Layer ◽  
Group Iii Nitrides ◽  
Alloy Layer ◽  
Field Pattern ◽  
Group Iii

In the field of group-III nitrides, hetero-epitaxial growth has been one of the most important key technologies. A thick layer of AlGaN alloy with higher AlN molar fraction is difficult to grow on sapphire substrate, because the alloy layer is easily cracked. It is thought that one cause of generating cracks is a large lattice mismatch between an AlGaN and a GaN, when AlGaN is grown on the underlying GaN layer. We have achieved crack-free Al0.07Ga0.93N layer with the thickness of more than 1μm using underlying Al0.05Ga0.95N layer. The underlying Al0.05Ga0.95N layer was grown directly on sapphire by using the low-temperature-deposited buffer layer (LT-buffer layer). Since a lattice mismatch between the underlying Al0.05Ga0.95N layer and upper Al0.07Ga0.93N layer is relatively small, the generation of cracks is thought to be suppressed. This technology is applied to a GaN-based laser diode structure, in which thick n-Al0.07Ga0.93N cladding layer grown on the Al0.05Ga0.95N layer, improves optical confinement and single-robe far field pattern in vertical direction.

Electronic and Optical Properties of the Group-III Nitrides, their Heterostructures and Alloys

1995 ◽  
Vol 395 ◽  
Author(s):  
Walter R. L. Lambrecht ◽  
Kwiseon Kim ◽  
Sergey N. Rashkeev ◽  
B. Segall
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Vacuum Ultraviolet ◽  
Lattice Mismatch ◽  
Group Iii Nitrides ◽  
Spin Orbit ◽  
Biaxial Strain ◽  
Strain Effects ◽  
Group Iii ◽  
Semiconductor Substrates

ABSTRACTVarious aspects of the electronic structure of the group III nitrides are discussed. The relation between band structures and optical response in the vacuum ultraviolet is analyzed for zincblende and wurtzite GaN and for wurtzite A1N and compared with available experimental data obtained from reflectivity and spectroscopic ellipsometry. The spin-orbit and crystal field splittings of the valence band edges and their relations to exciton fine structure are discussed including substrate induced biaxial strain effects. The band-offsets between the III-nitrides and some relevant semiconductor substrates obtained within the dielectric midgap energy model are presented and strain effects which may alter these values are discussed. The importance of lattice mismatch in bandgap bowing is exemplified by comparing AlxGa1−xN and InxGa1−xN.

The role of gaseous species in group-III nitride growth

1997 ◽  
Vol 2 ◽  
Author(s):  
S. Yu. Karpov ◽  
Yu. N. Makarov ◽  
M. S. Ramm
Keyword(s):  
Defect Formation ◽  
Lattice Mismatch ◽  
Solid Phase ◽  
Molecular Nitrogen ◽  
Group Iii Nitrides ◽  
Miscibility Gap ◽  
Gaseous Species ◽  
Group Iii ◽  
Ternary Compounds ◽  
Group Iii Nitride

A quasi-thermodynamic model accounting for kinetics of molecular nitrogen evaporation is applied to simulate the growth of binary and ternary group-III nitrides using atomic group-III elements and molecular ammonia as the sources. The values of the molecular nitrogen evaporation coefficients from the surface of GaN and AlN necessary for the simulation are extracted from experiments on free evaporation of the crystals in vacuum, while for InN only estimates are available. The growth process of AlN and InN is studied by analyzing the composition of the desorbed vapor species that are thought to influence the native defect formation in group-III nitrides. Different channels of desorption from the surfaces of group-III nitrides (related either to group-III atoms or to their hydrides) are compared. Specific features of the growth processes under the metal-rich and N-rich conditions are analyzed. The developed approach is extended to study the growth of the ternary compounds GaInN and AlGaN. The growth rate of ternary compounds versus temperature shows a two-drop behavior corresponding to the rapid increase of the respective group-III atom desorption. The effect is accompanied by a corresponding stepwise change in the solid phase composition. Factors retarding the growth of ternary compounds — the miscibility gap related to internal strain accumulated in the solid phase due to the lattice mismatch of binary constituents, and the extra liquid phase formation during growth — are discussed with respect to GaInN.

Phonon Modes in AlGaN Alloy with AlGaN/GaN MQW Interlayer

2011 ◽  
Vol 214 ◽  
pp. 526-530
Author(s):  
Jin Zhou ◽  
Yu Feng Jin ◽  
En Guang Dai ◽  
Zhi Jian Yang ◽  
Bo Shen
Keyword(s):  
Lattice Mismatch ◽  
Thick Layer ◽  
Alloy Layer ◽  
Green Laser ◽  
Uv Detector ◽  
Phonon Modes ◽  
Tunneling Diodes ◽  
Ion Laser ◽  
Mismatch Stress ◽  
Band Gap Structure

500nm AlGaN thick layer with AlGaN/GaN MQW interlayer was grown on sapphire substrate for UV detector and resonant tunneling diodes by MOCVD equipment. We were strongly interesting in the stress information of QW. There are a big mismatch of lattice between AlN and GaN.The growth of thick and high quality AlGaN is difficult task. AlGaN/GaN MQW layers were designed to relax the big mismatch stress. Many researcher focused on the stress relax mechanism for the growth of AlGaN alloy. The stress in QW can change the band gap structure and carrier contents of polarize induced charge. Raman spectra were a useful tool to observe the stress of semiconductor materials without damaging the sample. Using 514nm green laser, we only obtained the phonon modes of GaN. So applying 325nm Ar ion laser, we can observed the phonon modes spectra of both AlGaN and GaN layers. According to resonance conditions, the phonon modes of 789.74 cm-1 was origin from AlGaN alloy layer. The phonon modes of 740.89 cm-1 and 575.06 cm-1 were origin from GaN layer. Compared to other results, GaN layer was compress strain. We determined that AlGaN/GaN MQW interlayer relaxed strain stress from lattice mismatch, and phonon modes were clearly observed.

In-Situ Transmission Elecron Microscopy (TEM) Study of the Nitridation of Basal Plane Sapphire by Reactive Molecular Beam Epitaxy (RMBE)

1997 ◽  
Vol 3 (S2) ◽  
pp. 475-476
Author(s):  
M. Yeadon ◽  
M.T. Marshall ◽  
J.M. Gibson
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
High Vacuum ◽  
High Energy ◽  
Substantial Improvement ◽  
Ultra High Vacuum ◽  
Sapphire Surface ◽  
Group Iii ◽  
Flat Surfaces

Group III-nitride thin films are currently of great interest for use in wide-bandgap semiconductor applications including UV lasers and light emitting diodes (LEDs). Sapphire (a-Al2O3) is currently the substrate of choice for the growth of GaN despite a large lattice mismatch. Growth of high quality GaN epilayers typically involves the deposition of a buffer layer of either AIN or GaN at a temperature well below that used for the growth of the active GaN layer. It has been found empirically that nitridation of the sapphire surface with nascent nitrogen prior to growth of the buffer layer results in a substantial improvement in film quality. Using a novel ultra-high vacuum (UHV) in-situ TEM with in-situ RMBE, we have studied the nitridation of the (0001) sapphire surface using transmission and reflection electron microscopy (REM), reflection high energy electron diffraction (RHEED) and Auger electron spectroscopy (AES).An electron-transparent sapphire TEM sample was annealed at 1400°C for 12 hours in flowing oxygen, to form atomically flat surfaces for our investigation.

TEM and AFM studies of structural defects in α-GaN films

1995 ◽  
Vol 53 ◽  
pp. 456-457
Author(s):  
W. Qian ◽  
M. Skowronski ◽  
M. De Graef ◽  
G. Rohrer ◽  
K. Doverspike ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Defect Density ◽  
Wide Band ◽  
Group Iii Nitrides ◽  
Structural Defects ◽  
Group Iii ◽  
Transmission Electron ◽  
Potential Applications ◽  
Related Group

Interest in wide band-gap GaN and related group-III nitrides has grown recently due to their potential applications for short wavelength optoelectronic devices. One of the main obstacles for their application is the high density of defects formed during heteroepitaxy. Though important progress has been made by using a low temperature A1N buffer layer% recently reported films still contain a defect density (mainly threading dislocations) on the order of 1010 cm-2. This paper reports our current studies of structural defects in α-GaN thin films grown on a-plane (110) and c-plane (0001) sapphire substrates by organometallic vapor phase epitaxy (OMVPE). Atomic force microscopy (AFM), conventional and high resolution transmission electron microscopy (TEM) were used to investigate the nature and origin of these defects.Single crystal α-GaN films were grown using a low temperature A1N or GaN buffer layer in an inductively-heated, water cooled, vertical OMVPE reactor operated at 57 torr.

Epitaxial growth of group III nitrides on silicon substrates via a reflective lattice-matched zirconium diboride buffer layer

2003 ◽  
Vol 82 (15) ◽  
pp. 2398-2400 ◽  
Author(s):  
J. Tolle ◽  
R. Roucka ◽  
I. S. T. Tsong ◽  
C. Ritter ◽  
P. A. Crozier ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Buffer Layer ◽  
Zirconium Diboride ◽  
Group Iii Nitrides ◽  
Silicon Substrates ◽  
Group Iii ◽  
Lattice Matched

In-Situ Study of NiO Growth on Textured Nickel Tape Using Environmental Scanning Electron Microscope (ESEM) and Hot Stage

2001 ◽  
Vol 7 (S2) ◽  
pp. 1276-1277
Author(s):  
Y. Akin ◽  
R.E. Goddard ◽  
W. Sigmund ◽  
Y.S. Hascicek
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Dip Coating ◽  
Buffer Layers ◽  
Superconducting Film ◽  
Environmental Scanning ◽  
Cold Rolling And Annealing

Deposition of highly textured ReBa2Cu3O7−δ (RBCO) films on metallic substrates requires a buffer layer to prevent chemical reactions, reduce lattice mismatch between metallic substrate and superconducting film layer, and to prevent diffusion of metal atoms into the superconductor film. Nickel tapes are bi-axially textured by cold rolling and annealing at appropriate temperature (RABiTS) for epitaxial growth of YBa2Cu3O7−δ (YBCO) films. As buffer layers, several oxide thin films and then YBCO were coated on bi-axially textured nickel tapes by dip coating sol-gel process. Biaxially oriented NiO on the cube-textured nickel tape by a process named Surface-Oxidation- Epitaxy (SEO) has been introduced as an alternative buffer layer. in this work we have studied in situ growth of nickel oxide by ESEM and hot stage.Representative cold rolled nickel tape (99.999%) was annealed in an electric furnace under 4% hydrogen-96% argon gas mixture at 1050°C to get bi-axially textured nickel tape.

scholarly journals MOCVD Grown HgCdTe Heterostructures for Medium Wave Infrared Detectors

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 611
Author(s):  
Waldemar Gawron ◽  
Jan Sobieski ◽  
Tetiana Manyk ◽  
Małgorzata Kopytko ◽  
Paweł Madejczyk ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Infrared Detectors ◽  
Lattice Mismatch ◽  
Layer Growth ◽  
Ex Situ ◽  
Current Status ◽  
Organic Chemical ◽  
Infrared Band ◽  
Donor And Acceptor ◽  
Wide Range

This paper presents the current status of medium-wave infrared (MWIR) detectors at the Military University of Technology’s Institute of Applied Physics and VIGO System S.A. The metal–organic chemical vapor deposition (MOCVD) technique is a very convenient tool for the deposition of HgCdTe epilayers, with a wide range of compositions, used for uncooled infrared detectors. Good compositional and thickness uniformity was achieved on epilayers grown on 2-in-diameter, low-cost (100) GaAs wafers. Most growth was performed on substrates, which were misoriented from (100) by between 2° and 4° in order to minimize growth defects. The large lattice mismatch between GaAs and HgCdTe required the usage of a CdTe buffer layer. The CdTe (111) B buffer layer growth was enforced by suitable nucleation procedure, based on (100) GaAs substrate annealing in a Te-rich atmosphere prior to the buffer deposition. Secondary-ion mass spectrometry (SIMS) showed that ethyl iodide (EI) and tris(dimethylamino)arsenic (TDMAAs) were stable donor and acceptor dopants, respectively. Fully doped (111) HgCdTe heterostructures were grown in order to investigate the devices’ performance in the 3–5 µm infrared band. The uniqueness of the presented technology manifests in a lack of the necessity of time-consuming and troublesome ex situ annealing.

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