scholarly journals Strain Modulation of Selectively and/or Globally Grown Ge Layers

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1421
Author(s):  
Yong Du ◽  
Guilei Wang ◽  
Yuanhao Miao ◽  
Buqing Xu ◽  
Ben Li ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Compressive Strain ◽  
Hole Mobility ◽  
Bandgap Energy ◽  
Threading Dislocation ◽  
High Quality ◽  
Threading Dislocation Density ◽  
Novel Method ◽  
Pl Intensity ◽  
Strain Modulation

This article presents a novel method to grow a high-quality compressive-strain Ge epilayer on Si using the selective epitaxial growth (SEG) applying the RPCVD technique. The procedures are composed of a global growth of Ge layer on Si followed by a planarization using CMP as initial process steps. The growth parameters of the Ge layer were carefully optimized and after cycle-annealing treatments, the threading dislocation density (TDD) was reduced to 3 × 107 cm−2. As a result of this process, a tensile strain of 0.25% was induced, whereas the RMS value was as low as 0.81 nm. Later, these substrates were covered by an oxide layer and patterned to create trenches for selective epitaxy growth (SEG) of the Ge layer. In these structures, a type of compressive strain was formed in the SEG Ge top layer. The strain amount was −0.34%; meanwhile, the TDD and RMS surface roughness were 2 × 106 cm−2 and 0.68 nm, respectively. HRXRD and TEM results also verified the existence of compressive strain in selectively grown Ge layer. In contrast to the tensile strained Ge layer (globally grown), enhanced PL intensity by a factor of more than 2 is partially due to the improved material quality. The significantly high PL intensity is attributed to the improved crystalline quality of the selectively grown Ge layer. The change in direct bandgap energy of PL was observed, owing to the compressive strain introduced. Hall measurement shows that a selectively grown Ge layer possesses room temperature hole mobility up to 375 cm2/Vs, which is approximately 3 times larger than that of the Ge (132 cm2/Vs). Our work offers fundamental guidance for the growth of high-quality and compressive strain Ge epilayer on Si for future Ge-based optoelectronics integration applications.

High quality AlN with uniform in-plane strain on nano-patterned AlN templates achieved by preset strain modulation

2021 ◽  
Author(s):  
Baiyin Liu ◽  
Fujun Xu ◽  
Jiaming Wang ◽  
Jing Lang ◽  
Na Zhang ◽  
...  
Keyword(s):  
Plane Strain ◽  
Light Emitting Diode ◽  
Compressive Strain ◽  
Light Output ◽  
Threading Dislocation ◽  
High Quality ◽  
Light Emitting ◽  
Threading Dislocation Density ◽  
Strain Modulation ◽  
Single Emission

Abstract High-quality AlN with uniform in-plane strain has been attempted with preset strain modulation on nano-patterned AlN templates (NPATs). It is found that this strain preset frame can effectively improve both the tilt and twist features of AlN on NPATs, further greatly decreasing threading dislocation density. More importantly, the AlN epilayer after completing coalescence can maintain the in-plane uniform compressive strain. Adopting AlN templates achieved in this scheme, the chip-on-wafer light output power (LOP) of AlGaN light-emitting diode (LED) reaches 10.2 mW at 100 mA with single emission peak at 280 nm, which increases by 22.3% than the LOP of LED device without adopting this strain preset frame.

Mid-10 cm−2 threading dislocation density in optimized high-Ge content relaxed graded SiGe on Si for III-V solar on Si

2004 ◽  
Vol 836 ◽  
Author(s):  
David M. Isaacson ◽  
Carl L. Dohrman ◽  
Arthur J. Pitera ◽  
Saurabh Gupta ◽  
Eugene A. Fitzgerald
Keyword(s):  
Solar Cells ◽  
Dislocation Density ◽  
Minority Carrier ◽  
Dislocation Nucleation ◽  
Threading Dislocation ◽  
High Quality ◽  
Significant Development ◽  
Threading Dislocation Density ◽  
Free Growth

ABSTRACTWe present a framework for obtaining high quality relaxed graded SiGe buffers on Si for III-V integration. By avoiding dislocation nucleation in Si1−xGex layers of x>0.96, we have achieved a relaxed Si0.04Ge0.96 platform on Si(001) offcut 2° that has a threading dislocation density of 7.4×105 cm−2. This 2° offcut orientation was determined to be the minimum necessary for APB-free growth of GaAs. Furthermore, we found that we could compositionally grade the Ge content in the high-Ge portion of the buffer at up to 17 %Ge μm−1 with no penalty to the dislocation density. The reduction in both threading dislocation density and buffer thickness exhibited by our method is an especially significant development for relatively thick minority-carrier devices which use III-V materials such as multi-junction solar cells.

Impact of the Growth Parameters on the Structural Properties of Si0.8Ge0.2 Virtual Substrates

2005 ◽  
Vol 108-109 ◽  
pp. 445-450 ◽  
Author(s):  
Y. Bogumilowicz ◽  
J.M. Hartmann ◽  
F. Laugier ◽  
G. Rolland ◽  
Thierry Billon
Keyword(s):  
Growth Rate ◽  
Structural Properties ◽  
Growth Parameters ◽  
Strain Relaxation ◽  
Chemical Vapour ◽  
Root Mean Square Roughness ◽  
Threading Dislocation ◽  
Reduced Pressure ◽  
Threading Dislocation Density ◽  
The Impact

We have focused in this paper on the impact of the growth rate and of the grading rate on the structural properties of Si0.8Ge0.2 virtual substrates grown at 900°C in a commercial reduced pressure chemical vapour deposition reactor. Adopting a grading rate of 4% Ge / $m together with a growth rate around 140 nm min.-1 yields very high quality Si0.8Ge0.2 virtual substrates. Their macroscopic degree of strain relaxation is indeed very close to 100%, their surface root mean square roughness is around 2.3 nm and most importantly their field threading dislocation density is of the order of 6x104 cm-2 only, with almost no pile-ups.

Engineering Dislocation Dynamics in Inx(AlyGa1−y)1−xP Graded Buffers Grown on Gap by Movpe

1998 ◽  
Vol 510 ◽  
Author(s):  
A.Y. Kim ◽  
E.A. Fitzgerald
Keyword(s):  
Surface Roughness ◽  
Dislocation Density ◽  
Growth Conditions ◽  
Dislocation Nucleation ◽  
Dislocation Dynamics ◽  
Threading Dislocation ◽  
High Quality ◽  
Movpe Growth ◽  
Threading Dislocation Density ◽  
Buffer Design

AbstractTo engineer high-quality Inx(AlyGa1−y)1−x P/Ga1−xP graded buffers, we have explored the effects of graded buffer design and MOVPE growth conditions on material quality. We demonstrate that surface roughness causes threading dislocation density (TDD) to increase with continued grading: dislocations and roughness interact in a recursive, escalating cycle to form pileups that cause increasing roughness and dislocation nucleation. Experiments show that V/III ratio, temperature, and grading rate can be used to control dislocation dynamics and surface roughness in InxGa1−xP graded buffers. Control of these parameters individually has resulted in x = 0.34 graded buffers with TDD = 5 × 106 cm−2and roughness = 15 nm and a simple optimization has resulted in TDD = 3 × 106 cm −2and roughness = 10 un. Our most recent work has focused on more sophisticated optimization and the incorporation of aluminum for x > 0.20 to keep the graded buffer completely transparent above 545 nm. Given our results, we expect to achieve transparent, device-quality Inx(AlyGa1−y)1−x P/GaP graded buffers with TDD < 106 cm−2

High Quality Germanium Photodiodes on Silicon Substrates Using an Intermediate Chemical Mechanical Polishing Step

1997 ◽  
Vol 486 ◽  
Author(s):  
Srikanth B. Samavedam ◽  
Matthew T. Currie ◽  
Thomas A. Langdo ◽  
Steve M. Ting ◽  
Eugene A. Fitzgerald
Keyword(s):  
Dislocation Density ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Quantum Yields ◽  
Threading Dislocation ◽  
Thermal Mismatch ◽  
High Quality ◽  
Si Substrates ◽  
Threading Dislocation Density ◽  
Graded Layers

AbstractGermanium (Ge) photodiodes are capable of high quantum yields and can operate at gigahertz frequencies in the 1–1.6 μm wavelength regime. The compatibility of SiGe alloys with Si substrates makes Ge a natural choice for photodetectors in Si-based optoelectronics applications. The large lattice mismatch (≈4%) between Si and Ge, however, leads to the formation of a high density of misfit and associated threading dislocations when uniform Ge layers are grown on Si substrates. High quality Ge layers were grown on relaxed graded SiGe/Si layers by ultra-high vacuum chemical vapor deposition (UHVCVD). Typically, as the Ge concentration in the graded layers increases, strain fields from underlying misfit dislocations result in increased surface roughness and the formation of dislocation pile-ups. The generation of pile-ups increases the threading dislocation density in the relaxed layers. In this study the pileup formation was minimized by growing on miscut (001) substrates employing a chemical mechanical polishing (CMP) step within the epitaxial structure. Other problems such as the thermal mismatch between Si and Ge, results in unwanted residual tensile stresses and surface microcracks when the substrates are cooled from the growth temperature. Compressive strain has been incorporated into the graded layers to overcome the thermal mismatch problem, resulting in crack-free relaxed cubic Ge on Si at room temperature. The overall result of the CMP step and the growth modifications have eliminated dislocation pile-ups, decreased gas-phase nucleation of particles, and eliminated the increase in threading dislocation density that occurs when grading to Ge concentrations greater than 70% Ge. The threading dislocation density in the Ge layers determined through plan view transmission electron microscopy (TEM) and etch pit density (EPD) was found to be in the range of 2 × 106/cm2. Ge p-n diodes were fabricated to assess the electronic quality and prove the feasibility of high quality photodetectors on Si substrates.

Analysis of EL Emitted by LEDs on Si Substrates Containing GeSn/Ge Multi Quantum Wells as Active Layers

2015 ◽  
Vol 242 ◽  
pp. 361-367 ◽  
Author(s):  
Bernhard Schwartz ◽  
Philipp Saring ◽  
Tzanimir Arguirov ◽  
Michael Oehme ◽  
Konrad Kostecki ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Heavy Hole ◽  
Compressive Strain ◽  
Threading Dislocation ◽  
Light Emitting ◽  
Si Substrates ◽  
Active Layers ◽  
Hole Band ◽  
Threading Dislocation Density ◽  
Multi Quantum Well

We analyzed multi quantum well light emitting diodes, consisting of ten alternating GeSn/Ge-layers, were grown by molecular beam epitaxy on Si. The Ge barriers were 10 nm thick and the GeSn wells were grown with 7% Sn and thicknesses between 6 and 12 nm. Despite the high threading dislocation density of 109to 1010cm−2the electroluminescence spectra measured at 300 and 80 K yield a broad and intensive luminescence band. Deconvolution revealed three major lines produced by the GeSn wells that can be interpreted in terms of quantum confinement. Biaxial compressive strain causes a splitting of light and heavy holes in the GeSn wells. We interpret the three lines to represent two direct lines, formed by transitions with the light and heavy hole band, respectively, andan indirect line.

scholarly journals High-quality GeSn Layer with Sn Composition up to 7% Grown by Low-temperature Magnetron Sputtering for Optoelectronic Application

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2662 ◽  
Author(s):  
Yang ◽  
Hu ◽  
Miao ◽  
Dong ◽  
Wang ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Optical Emission ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
High Quality ◽  
Rocking Curve ◽  
Optoelectronic Application ◽  
Current Voltage ◽  
Dislocation Densities ◽  
Novel Method

In this paper, a high-quality sputtered-GeSn layer on Ge (100) with a Sn composition up to 7% was demonstrated. The crystallinity of the GeSn layer was investigated via high-resolution X-ray diffraction (HR-XRD) and the strain relaxation degree of the GeSn layer was evaluated to be approximately 50%. A novel method was also proposed to evaluate the averaged threading dislocation densities (TDDs) in the GeSn layer, which was obtained from the rocking curve of GeSn layer along the (004) plane. The photoluminescence (PL) measurement result shows the significant optical emission (1870 nm) from the deposited high-quality GeSn layer. To verify whether our deposited GeSn can be used for optoelectronic devices, we fabricated the simple vertical p-i-n diode, and the room temperature current–voltage (I–V) characteristic was obtained. Our work paves the way for future sputtered-GeSn optimization, which is critical for optoelectronic applications.

Optical study of SiGe films grown with low temperature Si buffer

2001 ◽  
Vol 673 ◽  
Author(s):  
Y. H. Luo ◽  
J. Wan ◽  
J. L. Liu ◽  
K. L. Wang
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Optical Study ◽  
High Quality ◽  
Atomic Force ◽  
Threading Dislocation Density

ABSTRACTIn this work, SiGe films on low temperature Si buffer layers were grown by solid-source molecular beam epitaxy and characterized by atomic force microscope, photoluminescence and Raman spectroscopy. Effects of the growth temperature and the thickness of the low temperature Si buffer were studied. It was demonstrated that using proper growth conditions of the low temperature Si buffer, the Si buffer became tensily strained and gave rise to the compliant effect. High-quality SiGe films with low threading dislocation density have been obtained.

High-Speed Growth of 4H-SiC Single Crystal Using Si-Cr Based Melt

2013 ◽  
Vol 740-742 ◽  
pp. 73-76 ◽  
Author(s):  
Motohisa Kado ◽  
Hironori Daikoku ◽  
Hidemitsu Sakamoto ◽  
Hiroshi Suzuki ◽  
Takeshi Bessho ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Single Crystal ◽  
High Speed ◽  
High Rate ◽  
Threading Dislocation ◽  
High Quality ◽  
X Ray ◽  
Interface Kinetics ◽  
Threading Dislocation Density ◽  
Rate Limiting

In this study, we have investigated the rate-limiting process of 4H-SiC solution growth using Si-Cr based melt, and have tried high-speed growth. It is revealed that the rate-limiting process of SiC growth under our experimental condition is interface kinetics, which can be controlled by such factors as temperature and supersaturation of carbon. By enhancing the interface kinetics, SiC crystal has been grown at a high rate of 2 mm/h. The FWHM values of X-ray rocking curves and threading dislocation density of the grown crystals are almost the same as those of seed crystal. Possibility of high-speed and high-quality growth of 4H-SiC has been indicated.

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