Defect controls by silicon doping in non-polar a-plane AlGaN epi-layers

Deposition of high-quality Si-doped crystalline AlGaN layers, especially non-polar-grown AlGaN layers, is critical and remains difficult in preparing AlGaN-based light-emitting diodes (LEDs), as the Si-doping-induced variations of crystalline structures are still under exploration. In this work, structural characterizations of Si-doped AlxGa1−xN layers were carried out by associating with examination of their carrier recombination behaviors in photoluminescence (PL) processes, to clarify the physical mechanism on how Si doping controls the formation of structural defects in AlGaN alloy. The obtained results showed that Si doping induced extrinsic shallow donor states and increased the densities of point defects like cation vacancies. On the contrary, Si doping suppressed formation of line defects like dislocations and planar defects like stacking faults with suitable doping concentration. These results may guide further improvement of UV-LEDs based on AlGaN alloy.

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Traps in Si-doped AlxGa1-xN Grown by Molecular Beam Epitaxy on Sapphire Characterized by Deep Level Transient Spectroscopy

MRS Proceedings ◽

10.1557/proc-0955-i15-30 ◽

2006 ◽

Vol 955 ◽

Author(s):

Mo Ahoujja ◽

S Elhamri ◽

M Hogsed ◽

Y. K. Yeo ◽

R. L. Hengehold

Keyword(s):

Molecular Beam Epitaxy ◽

Deep Level Transient Spectroscopy ◽

Molecular Beam ◽

Deep Level ◽

Unknown Origin ◽

Shallow Donor ◽

Related Point ◽

Line Defects ◽

Si Doped ◽

Transient Spectroscopy

ABSTRACTDeep levels in Si doped AlxGa1−xN samples, with Al mole fraction in the range of x = 0 to 0.30, grown by radio-frequency plasma activated molecular beam epitaxy on sapphire substrates were characterized by deep level transient spectroscopy (DLTS). DLTS measurements show two significant electron traps, P1 and P2, in AlGaN at all aluminum mole fractions. The electron trap, P2, appears to be a superposition of traps A and B , both of which are observed in GaN grown by various growth techniques and are thought to be related to VGa-shallow donor complexes. Trap P1 is related to line defects and N-related point defects. Both of these traps are distributed throughout the bulk of the epitaxial layer. An additional trap P0 which was observed in Al0.20Ga0.80N and Al0.30Ga0.70N is of unknown origin, but like P1 and P2, it exhibits dislocation-related capture kinetics. The activation energy measured from the conduction band of the defects is found to increase with Al mole content, a behavior consistent with other III-V semiconductors.

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Tuning the deformation mechanisms of boron carbide via silicon doping

Science Advances ◽

10.1126/sciadv.aay0352 ◽

2019 ◽

Vol 5 (10) ◽

pp. eaay0352 ◽

Cited By ~ 2

Author(s):

Sisi Xiang ◽

Luoning Ma ◽

Bruce Yang ◽

Yvonne Dieudonne ◽

George M. Pharr ◽

...

Keyword(s):

Boron Carbide ◽

Shear Bands ◽

Deformation Mechanisms ◽

Shear Stresses ◽

High Shear ◽

Silicon Doping ◽

Si Doping ◽

Si Doped ◽

Solute Atoms ◽

Loss Of Strength

Boron carbide suffers from a loss of strength and toughness when subjected to high shear stresses due to amorphization. Here, we report that a small amount of Si doping (~1 atomic %) leads to a substantial decrease in stress-induced amorphization due to a noticeable change of the deformation mechanisms in boron carbide. In the undoped boron carbide, the Berkovich indentation–induced quasi-plasticity is dominated by amorphization and microcracking along the amorphous shear bands. This mechanism resulted in long, distinct, and single-variant shear faults. In contrast, substantial fragmentation with limited amorphization was activated in the Si-doped boron carbide, manifested by the short, diffuse, and multivariant shear faults. Microcracking via fragmentation competed with and subsequently mitigated amorphization. This work highlights the important roles that solute atoms play on the structural stability of boron carbide and opens up new avenues to tune deformation mechanisms of ceramics via doping.

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Improved Performance of GaN-Based Ultraviolet LEDs with the Stair-like Si-Doping n-GaN Structure

Crystals ◽

10.3390/cryst11101203 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1203

Author(s):

Xiaomeng Fan ◽

Shengrui Xu ◽

Hongchang Tao ◽

Ruoshi Peng ◽

Jinjuan Du ◽

...

Keyword(s):

Dislocation Density ◽

Light Output ◽

Current Crowding ◽

X Ray Diffraction ◽

Light Emitting ◽

Si Doping ◽

Uv Led ◽

Wall Plug Efficiency ◽

Improved Performance ◽

Uv Leds

A method to improve the performance of ultraviolet light-emitting diodes (UV-LEDs) with stair-like Si-doping GaN layer is investigated. The high-resolution X-ray diffraction shows that the UV-LED with stair-like Si-doping GaN layer possesses better quality and a lower dislocation density. In addition, the experimental results demonstrate that light output power and wall plug efficiency of UV-LED with stair-like Si-doping GaN are significantly improved. Through the analysis of the experimental and simulation results, we can infer that there are two reasons for the improvement of photoelectric characteristics: reduction of dislocation density and alleviating of current crowding of UV-LEDs by introduced stair-like Si-doping GaN.

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Low Resistive and Low Absorptive Nitride-Based Tunnel junctions

MRS Proceedings ◽

10.1557/opl.2015.139 ◽

2015 ◽

Vol 1736 ◽

Author(s):

Daichi Minamikawa ◽

Daiki Takasuka ◽

Masataka Ino ◽

Motoaki Iwaya ◽

Tetsuya Takeuchi ◽

...

Keyword(s):

Tunnel Junction ◽

Reverse Bias ◽

Tunnel Junctions ◽

Voltage Drop ◽

Hole Injection ◽

Si Doping ◽

Si Doped ◽

Deep Uv ◽

Uv Leds ◽

Mg Doped

ABSTRACTWe have investigated two approaches for an alternative hole injection with a tunnel junction targeting deep UV-LEDs. One was an AlGaN-based tunnel junction. We fabricated the AlGaN-based tunnel junctions with various AlN mole fractions (0～0.2) grown on conventional blue-LEDs by MOVPE. A 7.5 nm heavily Mg-doped GaN/15 nm heavily Si-doped Al0.2Ga0.8N tunnel junction showed a large voltage drop, 5.31 V at 20 mA, under reverse bias. The other was a GaInN-based tunnel junction. We prepared Ga0.6In0.4N tunnel junctions with various thicknesses and Si doping levels grown on the blue LEDs by MOVPE. A 2 nm heavily Mg-doped Ga0.6In0.4N/3 nm heavily Si-doped GaN tunnel junction showed only 0.12 V drop at 20mA under reverse bias. Since an absorption of the thin GaInN tunnel junction was estimated to be less than 10 %, such a tunnel junction with small bandgap and thin layer thickness is a practical approach to obtain a low resistive and low absorptive hole injection in the deep UV-LEDs.

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Fabrication of p-n junction with Mg-doped wide bandgap InAlGaN for application to UV emitters

MRS Proceedings ◽

10.1557/proc-693-i4.10.1 ◽

2001 ◽

Vol 693 ◽

Cited By ~ 1

Author(s):

H. Hirayama ◽

T. Yamanaka ◽

A. Kinoshita ◽

K. Hiraoka ◽

A. Hirata ◽

...

Keyword(s):

Room Temperature ◽

Deep Level ◽

Uv Light ◽

Wide Bandgap ◽

Light Emitting ◽

Uv Emission ◽

Si Doped ◽

Uv Leds ◽

Uv Emitters ◽

Mg Doped

AbstractMg-doped quaternary InAlGaN is very attractive for use as p-side layers of 300-nm band ultraviolet (UV) light-emitting diodes (LEDs) or laser diodes (LDs), because high hole conductivity is expected to obtain for wide bandgap (~4 eV) InAlGaN with Mg-doping. We fabricated p-n junction diode consisting of Mg-doped In0.02Al0.28Ga0.70N and Si-doped Al0.25Ga0.75N, and demonstrated intense UV emission under CW current injection at room temperature. The rising voltage in I-V curve was around 3.8 V and the breakdown voltage was as high as 10 V. Single peaked intense emission was observed at 340 nm from around InAlGaN/AlGaN p-n junction area without any deep level emission. Also we found that Ni/Au electrode directly fabricated on Mg-doped InAlGaN is useful. From these results, Mg-doped InAlGaN is considered to be very attractive for use as p-side layer of UV-LEDs or LDs.

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Effects of Silicon Doping and Threading Dislocation Density on Stress Evolution in AlGaN Films

MRS Proceedings ◽

10.1557/opl.2012.215 ◽

2012 ◽

Vol 1396 ◽

Author(s):

Joan M. Redwing ◽

Ian C. Manning ◽

Xiaojun Weng ◽

Sarah M. Eichfeld ◽

Jeremy D. Acord ◽

...

Keyword(s):

Compressive Stress ◽

Stress Gradient ◽

Chemical Vapor ◽

Growth Stress ◽

Film Stress ◽

Threading Dislocation ◽

Silicon Doping ◽

Dislocation Interaction ◽

Si Doping ◽

Si Doped

ABSTRACTIn-situ wafer curvature measurements were used to study the effect of Si doping on intrinsic growth stress during the metalorganic chemical vapor deposition (MOCVD) growth of AlxGa1-xN (x=0-0.62) layers on SiC substrates. Post-growth transmission electron microscopy (TEM) characterization was used to correlate measured changes in stress with changes in film microstructure. Si doping was found to result in the inclination of edge-type threading dislocations (TDs) in AlxGa1-xN which resulted in a relaxation of compressive stress and generation of tensile stress. The experimentally measured stress gradient was similar to that predicted by an effective climb model. Dislocation inclination resulted in a reduction in the TD density for Si-doped layers compared to undoped AlxGa1-xN likely due to increased opportunities for dislocation interaction and annihilation. The TD density, which increased with increasing Al-fraction, was found to significantly alter the stress gradients in the films. Film stress was also observed to play a role in TD inclination. In undoped AlxGa1-xN, TD inclination was observed only when the film grew under a compressive stress while in Si-doped AlxGa1-xN, TD inclination was observed independent of the sign or magnitude of the film stress. Si dopants are believed to alter the concentration of surface vacancies which gives rise to dislocation jog via a surface-mediated climb mechanism.

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Characterization and Elimination of Forward Snapback Defects in GaAs Light Emitting Diodes

ISTFA 1996: Conference Proceedings from the 22nd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa1996p0239 ◽

1996 ◽

Author(s):

J. Zimmer ◽

D. Nielsen ◽

T.A. Anderson ◽

M. Schade ◽

N. Saha ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Light Emitting Diode ◽

Elevated Concentration ◽

Forward Voltage ◽

Light Emitting ◽

Intermittent Yield ◽

Si Doped ◽

Secondary Ion ◽

Furnace Pressure

Abstract The p-n junction of a GaAs light emitting diode is fabricated using liquid phase epitaxy (LPE). The junction is grown on a Si doped (~1018/cm3) GaAs substrate. Intermittent yield loss due to forward voltage snapback was observed. Historically, out of specification forward voltage (Vf) parameters have been correlated to abnormalities in the junction formation. Scanning electron (SEM) and optical microscopy of cleaved and stained samples revealed a continuous layer of material approximately 2.5 to 3.0 urn thick at the n-epi/substrate interface. Characterization of a defective wafer via secondary ion mass spectroscopy (SIMS) revealed an elevated concentration of O throughout the region containing the defect. X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) data taken from a wafer prior to growth of the epi layers did not reveal any unusual oxidation or contamination. Extensive review of the processing data suggested LPE furnace pressure was the obvious source of variability. Processing wafers through the LPE furnace with a slight positive H2 gas pressure has greatly reduced the occurrence of this defect.

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