| 1. |
- Junesand, Carl, et al.
(författare)
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Defect reduction in heteroepitaxial InP on Si by epitaxial lateral overgrowth
- 2014
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Ingår i: Materials Express. - : American Scientific Publishers. - 2158-5849 .- 2158-5857. ; 4:1, s. 41-53
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial lateral overgrowth of InP has been grown by hydride vapor phase epitaxy on Si substrates with a thin seed layer of InP masked with SiO2. Openings in the form of multiple parallel lines as well as mesh patterns from which growth occurred were etched in the SiO2 mask and the effect of different growth conditions in terms of V/III ratio and growth temperature on defects such as threading dislocations and stacking faults in the grown layers was investigated. The samples were characterized by cathodoluminescence and by transmission electron microscopy. The results show that the cause for threading dislocations present in the overgrown layers is the formation of new dislocations, attributed to coalescence of merging growth fronts, possibly accompanied by the propagation of pre-existing dislocations through the mask openings. Stacking faults were also pre-existing in the seed layer and propagated to some extent, but the most important reason for stacking faults in the overgrown layers was concluded to be formation of new faults early during growth. The formation mechanism could not be unambiguously determined, but of several mechanisms considered, incorrect deposition due to distorted bonds along overgrowth island edges was found to be in best agreement with observations.
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| 2. |
- Metaferia, Wondwosen, 1980-, et al.
(författare)
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High quality InP nanopyramidal frusta on Si
- 2014
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033 .- 1466-8033. ; 16:21, s. 4624-4632
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Tidskriftsartikel (refereegranskat)abstract
- Nanosized octagonal pyramidal frusta of indium phosphide were selectively grown at circular hole openings on a silicon dioxide mask deposited on indium phosphide and indium phosphide pre-coated silicon substrates. The eight facets of the frusta were determined to be {111} and {110} truncated by a top (100) facet. The size of the top flat surface can be controlled by the diameter of the openings in the mask and the separation between them. The limited height of the frusta is attributed to kinetically controlled selective growth on the (100) top surface. Independent analyses with photoluminescence, cathodoluminescence and scanning spreading resistance measurements confirm certain doping enrichment in the frustum facets. This is understood to be due to crystallographic orientation dependent dopant incorporation. The blue shift from the respective spectra is the result of this enrichment exhibiting the Burstein-Moss effect. Very bright panchromatic cathodoluminescence images indicate that the top surfaces of the frusta are free from dislocations. The good optical and morphological quality of the nanopyramidal frusta indicates that the fabrication method is very attractive for the growth of site-, shape-, and number-controlled semiconductor quantum dot structures on silicon for nanophotonic applications.
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| 3. |
- Sun, Yanting, et al.
(författare)
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Optical and structural properties of sulfur-doped ELOG InP on Si
- 2015
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 117:21
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Tidskriftsartikel (refereegranskat)abstract
- Optical and structural properties of sulfur-doped epitaxial lateral overgrowth (ELOG) InP grown from nano-sized openings on Si are studied by room-temperature cathodoluminescence and cross-sectional transmission electron microscopy (XTEM). The dependence of luminescence intensity on opening orientation and dimension is reported. Impurity enhanced luminescence can be affected by the facet planes bounding the ELOG layer. Dark line defects formed along the [011] direction are identified as the facet planes intersected by the stacking faults in the ELOG layer. XTEM imaging in different diffraction conditions reveals that stacking faults in the seed InP layer can circumvent the SiO2 mask during ELOG and extend to the laterally grown layer over the mask. A model for Suzuki effect enhanced stacking fault propagation over the mask in sulfur-doped ELOG InP is constructed and in-situ thermal annealing process is proposed to eliminate the seeding stacking faults.
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| 4. |
- Fan, Zhaozhong, et al.
(författare)
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Oxygen-Bridged Indium-Nickel Atomic Pair as Dual-Metal Active Sites Enabling Synergistic Electrocatalytic CO2 Reduction
- 2023
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 62:7
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Tidskriftsartikel (refereegranskat)abstract
- Single-atom catalysts offer a promising pathway for electrochemical CO2 conversion. However, it is still a challenge to optimize the electrochemical performance of dual-atom catalysts. Here, an atomic indium-nickel dual-sites catalyst bridged by an axial oxygen atom (O-In-N6-Ni moiety) was anchored on nitrogenated carbon (InNi DS/NC). InNi DS/NC exhibits superior CO selectivity with Faradaic efficiency higher than 90 % over a wide potential range from −0.5 to −0.8 V versus reversible hydrogen electrode (vs. RHE). Moreover, an industrial CO partial current density up to 317.2 mA cm−2 is achieved at −1.0 V vs. RHE in a flow cell. In situ ATR-SEIRAS combined with theory calculations reveal that the synergistic effect of In-Ni dual-sites and O atom bridge not only reduces the reaction barrier for the formation of *COOH, but also retards the undesired hydrogen evolution reaction. This work provides a feasible strategy to construct dual-site catalysts towards energy conversion.
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| 5. |
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| 6. |
- Kataria, Himanshu, et al.
(författare)
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Carrier-transport, optical and structural properties of large area ELOG InP on Si using conventional optical lithography
- 2013
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Ingår i: 2013 International Conference on Indium Phosphide and Related Materials (IPRM). - : IEEE conference proceedings. - 9781467361309 - 9781467361316 ; , s. 6562592-
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Konferensbidrag (refereegranskat)abstract
- We present the carrier-transport, optical and structural properties of InP deposited on Si by Epitaxial Lateral Overgrowth (ELOG) in a Low Pressure-Hydride Vapor phase epitaxy (LP-HVPE). Hall measurements, micro photoluminescence (μ-PL) and X-ray diffraction (XRD) were used to study the above-mentioned respective properties at room temperature. It is the first time that electrical properties of ELOG InP on Si are studied by Hall measurements. Prior to ELOG, etching of patterned silicon dioxide (SiO2) mask leading to a high aspect ratio, i. e. mask thickness to opening width >2 was optimized to eliminate defect propagation even above the opening. Dense high aspect ratio structures were fabricated in SiO2 to obtain ELOG InP on Si, coalesced over large area, making it feasible to perform Hall measurements. We examine this method and study Hall mobility, strain and optical quality of large area ELOG InP on Si.
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| 7. |
- Kataria, Himanshu, et al.
(författare)
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Monolithic integration of InP based structures on silicon for optical interconnects
- 2014
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Ingår i: 2014 ECS and SMEQ Joint International Meeting. - : The Electrochemical Society. ; , s. 523-531
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Konferensbidrag (refereegranskat)abstract
- Monolithic integration of InP based structures on Si for optical interconnects is presented. Different strategies are demonstrated to achieve requisite InP platform on Si. In the first strategy, defect free isolated areas of epitaxially and laterally overgrown InP are obtained on Si and the InGaAsP based quantum wells directly grown on these templates have shown high material quality with uniform interfaces. In the second strategy, selective area growth is exploited to achieve InP nano pyramids on Si which can be used for the growth of quantum dot structures. In the third and the final strategy, a method is presented to achieve direct interface between InP and Si using corrugated epitaxial lateral overgrowth.
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| 8. |
- Li, Feng, et al.
(författare)
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Coating of Phosphide Catalysts on p-Silicon by a Necking Strategy for Improved Photoelectrochemical Characteristics in Alkaline Media
- 2021
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:17, s. 20185-20193
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Tidskriftsartikel (refereegranskat)abstract
- The methodology of coating electrocatalysts on semiconductor substrates is critical for the catalytic performance of photoelectrochemical electrodes. A weakly bound coating leads to orders of magnitude lower efficiency and reliability compared to those required to meet the commercial demand. Herein, a facile strategy based on the hydrolysis of TiCl4 is developed to solve the coating issue. Mesoporous tungsten phosphide (WP) particles were spin-coated and affixed onto TiO2-protected planar p-Si by the formation of a TiO2 necking layer between the catalyst particles and the substrates. Under 1 sun illumination, the as-prepared WP/TiO2/Si photocathode yields a saturated current density of -35 mA cm(-2) and a durability of over 110 h with a current density over -15 mA cm(-2) at 0 V versus a reversible hydrogen electrode in a 1.0 M KOH solution, which is among the state-of-the-art performances of commercial planar Si-based photocathodes. The Kelvin probe force microscopy results suggest the successive transfer of photoelectrons from Si to TiO2 and WP. The as-formed TiO2 necking layer plays the key role in ensuring the surface catalytic activity and durability. This necking strategy is also applicable for coating other transition-metal phosphides, for example, MoP and FeP, thus offering a practical approach to meet the commercial requirement of low-cost, highly efficient, and durable photoelectrodes.
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| 9. |
- Lourdudoss, Sebastian, et al.
(författare)
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Novel routes in heteroepitaxy and selective area growth for nanophotonics
- 2008
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Ingår i: Quantum Sensing and Nanophotonic Devices V. - : SPIE. - 9780819470751 ; , s. H9000-H9000
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Konferensbidrag (refereegranskat)abstract
- Integration of active photonic components on silicon and silicon on insulator (SOI) would be versatile for nanophotonics since CMOS compatible processes are available for fabricating passive devices on Si/SOI. Selective area growth of III-V semiconductors is also attractive for realising periodic structures for nanophotonics. Here we report on the recent results of high quality InP on Si and InP on SOI achieved by means of nanopatterning. MQW structures have been realised on InP/Si and InP/SOI. We would elaborate routes for monolithic integration of active and passive devices for nanophotonics.
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| 10. |
- Metaferia, Wondwosen, et al.
(författare)
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Demonstration of a quick process to achieve buried heterostructure quantum cascade laser leading to high power and wall plug efficiency
- 2014
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 53:8, s. 087104-
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Tidskriftsartikel (refereegranskat)abstract
- Together with the optimal basic design, buried heterostructure quantum cascade laser (BH-QCL) with semi-insulating regrowth offers a unique possibility to achieve an effective thermal dissipation and lateral single mode. We demonstrate here the realization of BH-QCLs with a single-step regrowth of highly resistive (>1 x 10(8) ohm . cm) semi-insulating InP: Fe in <45 min for the first time in a flexible hydride vapor phase epitaxy process for burying ridges etched down to 10 to 15 mu m depth, both with and without mask overhang. The fabricated BH-QCLs emitting at similar to 4.7 and similar to 5.5 mu m were characterized. 2-mm-long 5.5-mu m lasers with a ridge width of 17 to 22 mu m, regrown with mask overhang, exhibited no leakage current. Large width and high doping in the structure did not permit high current density for continuous wave (CW) operation. 5-mm-long 4.7-mu m BH-QCLs of ridge widths varying from 6 to 14 mu m regrown without mu mask overhang, besides being spatially monomode, TM00, exhibited wall plug efficiency (WPE) of similar to 8 to 9% with an output power of 1.5 to 2.5 W at room temperature and under CW operation. Thus, we demonstrate a quick, flexible, and single-step regrowth process with good planarization for realizing buried QCLs leading to monomode, high power, and high WPE.
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