| 1. |
|
|
| 2. |
- Omanakuttan, Giriprasanth, et al.
(författare)
-
Surface emitting 1.5 mu m multi-quantum well LED on epitaxial lateral overgrowth InP/Si
- 2020
-
Ingår i: Optical Materials Express. - : The Optical Society. - 2159-3930 .- 2159-3930. ; 10:7, s. 1714-1723
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a surface emitting 1.5 mu m multi-quantum well (MQW) light-emitting diode (LED) on a 3-inch epitaxial lateral overgrowth (ELOG) InP/Si wafer. The enhanced crystalline quality of ELOG InP/Si is revealed by various characterization techniques, which gives rise to a MQW with high photoluminescence intensity at 1.5 mu m and interference fringes arising from the vertical Fabry-Perot cavity. The LED devices exhibited strong electroluminescence intensity that increased with pump current. Moreover, transparency current measurements indicate optical gain in the 1.5 mu m MQW on InP/Si. The results are encouraging for obtaining wafer scale 1.5 mu m surface emitting laser structures on silicon with further optimization.
|
|
| 3. |
|
|
| 4. |
- Junesand, Carl, et al.
(författare)
-
Defect reduction in heteroepitaxial InP on Si by epitaxial lateral overgrowth
- 2014
-
Ingår i: Materials Express. - : American Scientific Publishers. - 2158-5849 .- 2158-5857. ; 4:1, s. 41-53
-
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.
|
|
| 5. |
- Junesand, Carl, et al.
(författare)
-
Effect of the Surface Morphology of Seed and Mask Layers on InP Grown on Si by Epitaxial Lateral Overgrowth
- 2012
-
Ingår i: Journal of Electronic Materials. - : Springer Verlag (Germany) / Institute of Electrical and Electronics Engineers (IEEE). - 0361-5235 .- 1543-186X. ; 41:9, s. 2345-2349
-
Tidskriftsartikel (refereegranskat)abstract
- Heteroepitaxy of InP on Si by epitaxial lateral overgrowth (ELOG) using a thin seed layer of InP as starting material is investigated, with special attention given to the effect of the surface morphology of the seed and the mask layers on the quality of the ELOG layers. Chemical mechanical polishing (CMP) has been used to improve the morphological and optical quality of InP grown by hydride vapor-phase epitaxy (HVPE) using ELOG. Two approaches have been investigated: polishing the InP seed layer on Si before depositing the SiO2 mask and polishing the SiO2 mask after its deposition on the unprocessed seed layer. For polishing the InP (seed)/Si, a two-step process with an aluminum oxide- and sodium hypochlorite-containing slurry as well as a slurry based on sodium hypochlorite mixed with citric acid was used. For SiO2 mask polishing, a slurry with colloidal silica as an abrasive was employed. In both cases, the SiO2 mask was patterned with double line openings and ELOG carried out in an HVPE reactor. Morphology and crystal quality of the resulting ELOG layers were studied with atomic force microscopy (AFM) and room-temperature panchromatic cathodoluminescence (PC-CL) in situ in a scanning electron microscope (SEM), respectively. The results show that, whereas both polishing approaches result in an ELOG InP layer with good morphology, its surface roughness is lower when the InP (seed)/Si is subjected to CMP prior to deposition of the SiO2 mask, than when only the SiO2 mask is polished. This approach also leads to a decrease in the number of defects generated during coalescence of the ELOG layers.
|
|
| 6. |
- Junesand, Carl, et al.
(författare)
-
Heteroepitaxial Growth of Indium Phosphide from Nano-openings Made by Masking on a Si(001) Wafer
- 2010
-
Ingår i: 2010 22ND INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE AND RELATED MATERIALS (IPRM). - 9781424459209
-
Konferensbidrag (refereegranskat)abstract
- We investigate nano-eptiaxial lateral overgrowth (NELOG) of InP from the nano-sized openings on a seed layer on the silicon wafer, by Hydride Vapor Phase Epitaxy (HVPE). The grown layers were analyzed by cathodoluminescence (CL) in situ a scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results from InP: S growth shows that the boundary plane of the grown layer has a major impact on the luminescence, indicating preferential orientation-dependent doping. Moreover, although there is clear evidence that most of the threading dislocations originating in the InP seed layer/Si interface are blocked by the mask, it appears that new dislocations are generated. Some of these dislocations are bounding planar defects such as stacking faults, possibly generated by unevenness in the mask. Finally, patterns where coalescence takes place at higher thickness seem to result in a rougher surface.
|
|
| 7. |
- Junesand, Carl, et al.
(författare)
-
Heteroepitaxial Indium Phosphide on Silicon
- 2010
-
Ingår i: SILICON PHOTONICS AND PHOTONIC INTEGRATED CIRCUITS II. - : SPIE. - 9780819481924 ; , s. Q-1-Q-9
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There is an intense interest on integration of III-V materials on silicon and silicon-on-insulator for realisation of optical interconnects, optical networking, imaging and disposable photonics for medical applications. Advances in photonic materials, structures and technologies are the main ingredients of this pursuit. We investigate nano epitaxial lateral overgrowth (NELOG) of InP material from the nano openings on a seed layer on the silicon wafer, by hydride vapour phase epitaxy (HVPE). The grown layers were analysed by cathodoluminescence (CL) in situ a scanning electron microscope, time-resolved photoluminescence (TR-PL), and atomic force microscope (AFM). The quality of the layers depends on the growth parameters such as the V/III ratio, growth temperature, and layer thickness. CL measurements reveal that the dislocation density can be as low as 2 - 3.10(7) cm(-2) for a layer thickness of similar to 6 mu m. For comparison, the seed layer had a dislocation density of similar to 1.10(9) cm(-2). Since the dislocation density estimated on theoretical grounds from TRPL measurements is of the same order of magnitude both for NELOG InP on Si and on InP substrate, the dislocation generation appears to be process related or coalescence related. Pertinent issues for improving the quality of the grown InP on silicon are avoiding damage in the openings due to plasma etching, pattern design to facilitate coalescence with minimum defects and choice of mask material compatible with InP to reduce thermal mismatch.
|
|
| 8. |
- Junesand, Carl, et al.
(författare)
-
Heterogeneous integration of indium phosphide on silicon by nano-epitaxial lateral overgrowth
- 2009
-
Ingår i: 2009 IEEE 21ST INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM). - 9781424434329 ; , s. 59-62
-
Konferensbidrag (refereegranskat)abstract
- InP on Si is grown by nano-epitaxial lateral overgrowth (nano-ELOG) on patterns consisting of net-type openings under different growth conditions. Analysis shows that net-type patterns yield large lateral growth rate and good optical quality. Different growth conditions have a substantial impact on growth rate and some effect on surface morphology, as well as on the optical quality. Optical quality is deemed to be affected partly by the amount of dislocations arising from the difference in thermal expansion coefficient between the mask and the InP layer, and partly by the layer thickness and surface morphology.
|
|
| 9. |
- Junesand, Carl, 1981-
(författare)
-
High-quality InP on Si and concepts for monolithic photonic integration
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As the age of Moore’s law is drawing to a close, continuing increase in computing performance is becoming increasingly hard‐earned, while demand for bandwidth is insatiable. One way of dealing with this challenge is the integration of active photonic material with Si, allowing high‐speed optical inter‐ and intra‐chip connects on one hand, and the economies of scale of the CMOS industry in optical communications on the other. One of the most essential active photonic materials is InP, stemming from its capability in combination with its related materials to produce lasers, emitting at wavelengths of 1300 and 1550 nm, the two most important wavelengths in data‐ and telecom.However, integrating InP with Si remains a challenging subject. Defects arise due to differences in lattice constants, differences in thermal expansion coefficients, polarity and island‐like growth behavior. Approaches to counter these problems include epitaxial lateral overgrowth (ELOG), which involves growing InP laterally from openings in a mask deposited on a defective InP/Si substrate. This approach solves some of these problems by filtering out the previously mentioned defects. However, filtering may not be complete and the ELOG and mask themselves may introduce new sources for formation of defects such as dislocations and stacking faults.In this work, the various kinds of defects present in InP ELOG layers grown by hydride vapor phase epitaxy on Si, and the reason for their presence, as well as strategies for counteracting them, are investigated. The findings reveal that whereas dislocations appear in coalesced ELOG layers both on InP and InP/Si, albeit to varying extents, uncoalesced ELOG layers on both substrate types are completely free of threading dislocations. Thus, coalescence is a critical aspect in the formation of dislocations. It is shown that a rough surface of the InP/Si substrate is detrimental to defect‐free coalescence. Chemical‐mechanical polishing of this surface improves the coalescence in subsequent ELOG leading to fewer defects.Furthermore, ELOG on InP substrate is consistently free of stacking faults. This is not the case for ELOG on InP/Si, where stacking faults are to some extent propagating from the defective substrate, and are possibly also forming during ELOG. A model describing the conditions for their propagation is devised; it shows that under certain conditions, a mask height to opening width aspect ratio of 3.9 should result in their complete blocking. As to the potential formation of new stacking faults, the formation mechanism is not entirely clear, but neither coalescence nor random deposition errors on low energy facets are the main reasons for their formation. It is hypothesized that the stacking faults can be removed by thermal annealing of the seed and ELOG layers.Furthermore, concepts for integrating an active photonic device with passive Si components are elucidated by combining Si/SiO2 waveguides used as the mask in ELOG and multi‐quantum well (MQW) lasers grown on ELOG InP. Such a device is found to have favorable thermal dissipation, which is an added advantage in an integrated photonic CMOS device.
|
|
| 10. |
- Junesand, Carl, et al.
(författare)
-
InP overgrowth on SiO2 for active photonic devices on silicon
- 2010
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering.
-
Konferensbidrag (refereegranskat)abstract
- ntegrationof III-V materials on silicon wafer for active photonic deviceshave previously been achieved by growing thick III-V layers ontop of silicon or by bonding the III-V stack layersonto a silicon wafer. Another way is the epitaxial lateralovergrowth (ELOG) of a thin III-V material from a seedlayer directly on the silicon wafer, which can be usedas a platform for the growth of active devices. Asa prestudy, we have investigated lateral overgrowth of InP byHydride Vapor Phase Epitaxy (HVPE) over SiO2 masks of differentthickness on InP substrates from openings in the mask. Openingswhich varied in direction, width and separation were made withE-beam lithography allowing a good dimension control even for nano-sizedopenings (down to 100 nm wide). This mimics overgrowth ofInP on top of SiO2/Si waveguides. By optimizing the growthconditions in terms of growth temperature and partial pressure ofthe source gases with respect to the opening direction, separationand width, we show that a thin (~200 nm) layerof InP with good morphology and crystalline quality can begrown laterally on top of SiO2. Due to the thingrown InP layer, amplification structures on top of it canbe well integrated with the underlying silicon waveguides. The proposedELOG technology provides a promising integration platform for hybrid InP/siliconactive devices.
|
|
