Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472341
M. Halsall, I. Crowe, R. Southern, P. Yang, R. Gwilliam
A series of Bismuth (Bi) doped silicon oxide layers were prepared by ion-implantation. All the samples exhibit strong room temperature near-infrared photoluminescence in the range 1.0μm-1.3μm which we assign to Bi related centres in the oxide matrix, similar to that reported previously for Bi doped oxides fabricated by alternative methods. The activation and sensitization of these luminescent centres was studied as a function of anneal temperature and co-doping with silicon (Si) and aluminium (Al). Comparision with Erbium doped films prepared in a similar way reveals comparable emission intensity from the Bi doped films. The even wider Bi-related luminescence makes this system very promising for use in on-chip, broadband lasers and amplifiers, particularly for use in telecommunications.
{"title":"Broadband near-infrared emission from bismuth doped silicon oxide films prepared by ion-implantation","authors":"M. Halsall, I. Crowe, R. Southern, P. Yang, R. Gwilliam","doi":"10.1109/COMMAD.2012.6472341","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472341","url":null,"abstract":"A series of Bismuth (Bi) doped silicon oxide layers were prepared by ion-implantation. All the samples exhibit strong room temperature near-infrared photoluminescence in the range 1.0μm-1.3μm which we assign to Bi related centres in the oxide matrix, similar to that reported previously for Bi doped oxides fabricated by alternative methods. The activation and sensitization of these luminescent centres was studied as a function of anneal temperature and co-doping with silicon (Si) and aluminium (Al). Comparision with Erbium doped films prepared in a similar way reveals comparable emission intensity from the Bi doped films. The even wider Bi-related luminescence makes this system very promising for use in on-chip, broadband lasers and amplifiers, particularly for use in telecommunications.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115258560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472346
N. Jiang, P. Parkinson, Q. Gao, J. Wong-Leung, S. Breuer, H. Tan, C. Jagadish
GaAs/AlxGa1-xAs core-shell nanowires were grown by metal organic chemical vapour deposition with Au-catalysed GaAs cores. Cross-section transmission electron microscope bright field images show that the tapering at bottom of the nanowires is mainly caused by GaAs cap growth. Time-resolved photo-luminescence measurements of single nanowires were taken at room temperature and a minority carrier lifetime of (1.02±0.43) ns was obtained for single nanowires with AlxGa1-xAs shell grown at 750°C. A close correlation between the shell growth temperature and minority carrier lifetime has also been observed.
{"title":"Improvement of minority carrier lifetime in GaAs/AlxGa1−xAs core-shell nanowires","authors":"N. Jiang, P. Parkinson, Q. Gao, J. Wong-Leung, S. Breuer, H. Tan, C. Jagadish","doi":"10.1109/COMMAD.2012.6472346","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472346","url":null,"abstract":"GaAs/AlxGa1-xAs core-shell nanowires were grown by metal organic chemical vapour deposition with Au-catalysed GaAs cores. Cross-section transmission electron microscope bright field images show that the tapering at bottom of the nanowires is mainly caused by GaAs cap growth. Time-resolved photo-luminescence measurements of single nanowires were taken at room temperature and a minority carrier lifetime of (1.02±0.43) ns was obtained for single nanowires with AlxGa1-xAs shell grown at 750°C. A close correlation between the shell growth temperature and minority carrier lifetime has also been observed.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124918427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472364
P. Prakash, M. Renilkumar, C. Venkatesh, L. Faraone, G. A. Umama-Membreno, K. Silva, A. Keating, M. Martyniuk, J. Dell, M. Varma, N. Bhat, R. Pratap
The design and analysis of an optical read-out scheme based on a grated waveguide (GWG) resonator for interrogating microcantilever sensor arrays is presented. The optical system consisting of a micro cantilever monolithically integrated in proximity to a grated waveguide (GWG), is realized in silicon optical bench platform. The mathematical analysis of the optical system is performed using a Fabry-Perot interferometer model with a lossy cavity formed between the cantilever and the GWG and an analytical expression is derived for the optical power transmission as a function of the cantilever deflection which corresponds to cavity width variation. The intensity transmission of the optical system for different cantilever deflections estimated using the analytical expression captures the essential features exhibited by a FDTD numerical model.
{"title":"Optical read-out scheme based on grated waveguide cantilever cavity resonance for interrogation of cantilever sensor arrays","authors":"P. Prakash, M. Renilkumar, C. Venkatesh, L. Faraone, G. A. Umama-Membreno, K. Silva, A. Keating, M. Martyniuk, J. Dell, M. Varma, N. Bhat, R. Pratap","doi":"10.1109/COMMAD.2012.6472364","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472364","url":null,"abstract":"The design and analysis of an optical read-out scheme based on a grated waveguide (GWG) resonator for interrogating microcantilever sensor arrays is presented. The optical system consisting of a micro cantilever monolithically integrated in proximity to a grated waveguide (GWG), is realized in silicon optical bench platform. The mathematical analysis of the optical system is performed using a Fabry-Perot interferometer model with a lossy cavity formed between the cantilever and the GWG and an analytical expression is derived for the optical power transmission as a function of the cantilever deflection which corresponds to cavity width variation. The intensity transmission of the optical system for different cantilever deflections estimated using the analytical expression captures the essential features exhibited by a FDTD numerical model.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123472086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472392
M. Sugiyama, H. Fujii, Y. Wen, Y. Wang, H. Sodabanlu, K. Watanabe, Y. Nakano
InGaAs/GaAsP quantum wells (QWs) have been inserted into a GaAs p-i-n cell aiming at a better current matching of an InGaP/GaAs/Ge tandem solar cell: photon absorption at a longer wavelength range than the GaAs bandedge was attempted while keeping pseudo-lattice-matching to GaAs for the QW structure as a whole. The efficient extraction of photo-generated carriers from the InGaAs wells to an external circuit was vital for minimizing the drop in open-circuit voltage, which necessitated extremely-thin (~3 nm) GaAsP barriers and tunnelling-assisted carrier transport. Such a superlattice structure was grown by metal-organic vapour-phase epitaxy (MOVPE) and evidenced a promising gain in current output. Under sunlight concentration (~100 suns), the open-circuit voltage of the GaAs p-i-n cell was almost unchanged upon the insertion of the superlattice and the superlattice just resulted in the gain in current output.
{"title":"InGaAs/GaAsP quantum-well superlattice solar cell for better carrier collection and higher efficiency","authors":"M. Sugiyama, H. Fujii, Y. Wen, Y. Wang, H. Sodabanlu, K. Watanabe, Y. Nakano","doi":"10.1109/COMMAD.2012.6472392","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472392","url":null,"abstract":"InGaAs/GaAsP quantum wells (QWs) have been inserted into a GaAs p-i-n cell aiming at a better current matching of an InGaP/GaAs/Ge tandem solar cell: photon absorption at a longer wavelength range than the GaAs bandedge was attempted while keeping pseudo-lattice-matching to GaAs for the QW structure as a whole. The efficient extraction of photo-generated carriers from the InGaAs wells to an external circuit was vital for minimizing the drop in open-circuit voltage, which necessitated extremely-thin (~3 nm) GaAsP barriers and tunnelling-assisted carrier transport. Such a superlattice structure was grown by metal-organic vapour-phase epitaxy (MOVPE) and evidenced a promising gain in current output. Under sunlight concentration (~100 suns), the open-circuit voltage of the GaAs p-i-n cell was almost unchanged upon the insertion of the superlattice and the superlattice just resulted in the gain in current output.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122641816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472399
H. Wang, P. Parkinson, J. Tian, D. Saxena, S. Mokkapati, Q. Gao, P. Prasai, L. Fu, F. Karouta, H. Tan, C. Jagadish
A single GaAs nanowire (NW) photodetector (PD) is fabricated based on the back-to-back Schottky diode structure. Optoelectronic properties are characterized by measuring device photocurrent, and also the spectral response, which indicates our device is very sensitive and applicable as a PD.
{"title":"Optoelectronic properties of GaAs nanowire photodetector","authors":"H. Wang, P. Parkinson, J. Tian, D. Saxena, S. Mokkapati, Q. Gao, P. Prasai, L. Fu, F. Karouta, H. Tan, C. Jagadish","doi":"10.1109/COMMAD.2012.6472399","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472399","url":null,"abstract":"A single GaAs nanowire (NW) photodetector (PD) is fabricated based on the back-to-back Schottky diode structure. Optoelectronic properties are characterized by measuring device photocurrent, and also the spectral response, which indicates our device is very sensitive and applicable as a PD.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"75 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128060165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472407
J. Sharp, W. J. Lee, G. Umana-Membreno, J. Dell, L. Faraone
Thin film and single crystal germanium solar cells are of interest for use in low cost thermophotovoltaics [1,2] and in multijunction solar cells. Single crystal Ge substrates have been utilised for the growth of high-efficiency III-V concentrator solar cells which have achieved high efficiencies [3]. In this paper, we consider the use of crystalline Ge as bottom cell and substrate for growth of high efficiency II-VI multijunction solar cells and amorphous Ge for application in thin film II-VI tandem solar cells.
{"title":"Single crystal and amorphous Ge for use in stand-alone and thin film tandem solar cells","authors":"J. Sharp, W. J. Lee, G. Umana-Membreno, J. Dell, L. Faraone","doi":"10.1109/COMMAD.2012.6472407","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472407","url":null,"abstract":"Thin film and single crystal germanium solar cells are of interest for use in low cost thermophotovoltaics [1,2] and in multijunction solar cells. Single crystal Ge substrates have been utilised for the growth of high-efficiency III-V concentrator solar cells which have achieved high efficiencies [3]. In this paper, we consider the use of crystalline Ge as bottom cell and substrate for growth of high efficiency II-VI multijunction solar cells and amorphous Ge for application in thin film II-VI tandem solar cells.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116125106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472414
N. Iwamoto, B. C. Johnson, N. Hoshino, M. Ito, H. Tsuchida, T. Ohshima
Defects in Schottky barrier diodes (SBDs) formed on low-doped 4H-silicon carbide (SiC) have been studied by charge transient spectroscopy using single high energy alpha particles as the trap filling pulse. We have successfully detected defect levels in as-fabricated, electron-irradiated and thermally annealed SBDs where the high series resistance precludes the use of standard techniques such as deep level transient spectroscopy (DLTS).
{"title":"Defect levels in low-doped 4H-SiC Schottky barrier diodes detected by using alpha particles","authors":"N. Iwamoto, B. C. Johnson, N. Hoshino, M. Ito, H. Tsuchida, T. Ohshima","doi":"10.1109/COMMAD.2012.6472414","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472414","url":null,"abstract":"Defects in Schottky barrier diodes (SBDs) formed on low-doped 4H-silicon carbide (SiC) have been studied by charge transient spectroscopy using single high energy alpha particles as the trap filling pulse. We have successfully detected defect levels in as-fabricated, electron-irradiated and thermally annealed SBDs where the high series resistance precludes the use of standard techniques such as deep level transient spectroscopy (DLTS).","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121293617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472405
J. Tollerud, G. Richards, H. Tan, C. Jagadish, J. Davis
A flexible, stable coherent multi-dimensional spectroscopy apparatus using spatial light modulators to shape beams temporally and spatially is developed and used to characterize coherent coupling dynamics in asymmetric GaAs double quantum wells.
{"title":"Demonstration of a stable and flexible coherent multi-dimensional spectroscopy apparatus to study coherent coupling in asymmetric double quantum wells","authors":"J. Tollerud, G. Richards, H. Tan, C. Jagadish, J. Davis","doi":"10.1109/COMMAD.2012.6472405","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472405","url":null,"abstract":"A flexible, stable coherent multi-dimensional spectroscopy apparatus using spatial light modulators to shape beams temporally and spatially is developed and used to characterize coherent coupling dynamics in asymmetric GaAs double quantum wells.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127188929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472423
G. Umana-Membreno, J. Sharp, A. Choudhary, J. Antoszewski, S. Dhar, S. Ryu, A. Agarwal, L. Faraone
Geometrical magnetoresistance measurements on 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFET) were performed under high magnetic field conditions (12T). Three n-channel samples were investigated with p-well acceptor concentrations of 5×1015 cm-3, 2×1017cm-3 and 2×1017cm-3. The results indicate relatively high carrier mobilities. However, the devices were found to be affected by a nearly quadratic dependence of the sheet electron density on gate bias. This behaviour is attributable to charge trapping in the channel.
{"title":"Magnetoresistance characterisation of 4H-SiC MOSFETs","authors":"G. Umana-Membreno, J. Sharp, A. Choudhary, J. Antoszewski, S. Dhar, S. Ryu, A. Agarwal, L. Faraone","doi":"10.1109/COMMAD.2012.6472423","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472423","url":null,"abstract":"Geometrical magnetoresistance measurements on 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFET) were performed under high magnetic field conditions (12T). Three n-channel samples were investigated with p-well acceptor concentrations of 5×10<sup>15</sup> cm<sup>-3</sup>, 2×10<sup>17</sup>cm<sup>-3</sup> and 2×10<sup>17</sup>cm<sup>-3</sup>. The results indicate relatively high carrier mobilities. However, the devices were found to be affected by a nearly quadratic dependence of the sheet electron density on gate bias. This behaviour is attributable to charge trapping in the channel.","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129114380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-01DOI: 10.1109/COMMAD.2012.6472424
M. Lysevych, H. Tan, F. Karouta, L. Fu, C. Jagadish
We present an InP-based laser with Y-coupling [1] inspired resonator cavity. This design allows the reduction of gain-saturation and two-photon absorption [2]. This is achieved by increasing the cross-section of laser mode (reducing the field intensity) while maintaining single spatial mode operation, which is very important in numerous semiconductor laser applications. This design can be applied to wide-waveguide lasers [3], as in this work, as well as to SCOWL (slab-coupled optical waveguide laser) [4].
{"title":"Reduction of gain-saturation in merged beam lasers","authors":"M. Lysevych, H. Tan, F. Karouta, L. Fu, C. Jagadish","doi":"10.1109/COMMAD.2012.6472424","DOIUrl":"https://doi.org/10.1109/COMMAD.2012.6472424","url":null,"abstract":"We present an InP-based laser with Y-coupling [1] inspired resonator cavity. This design allows the reduction of gain-saturation and two-photon absorption [2]. This is achieved by increasing the cross-section of laser mode (reducing the field intensity) while maintaining single spatial mode operation, which is very important in numerous semiconductor laser applications. This design can be applied to wide-waveguide lasers [3], as in this work, as well as to SCOWL (slab-coupled optical waveguide laser) [4].","PeriodicalId":136573,"journal":{"name":"COMMAD 2012","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128987719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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