Fused fiber components are critical building blocks for power scaling and reliable operation of fiber laser systems. We review different fiber fusion methods for fabricating fused fiber components, and show some examples of splicing of dissimilar fibers, fiber combiners, and fiber caps with high power handling capability, which enable power scaling of fiber lasers.
{"title":"Latest advances on fused fiber components for power scaling of fiber lasers","authors":"B. Wang, J. Faustino","doi":"10.1117/12.2081752","DOIUrl":"https://doi.org/10.1117/12.2081752","url":null,"abstract":"Fused fiber components are critical building blocks for power scaling and reliable operation of fiber laser systems. We review different fiber fusion methods for fabricating fused fiber components, and show some examples of splicing of dissimilar fibers, fiber combiners, and fiber caps with high power handling capability, which enable power scaling of fiber lasers.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131828247","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}
Nelson Cardenas, Matthew Kyrish, Daniel Taylor, M. Fraelich, Oscar M. Lechuga, R. Claytor, N. Claytor
Electro-Chemical Polishing is routinely used in the anodizing industry to achieve specular surface finishes of various metals products prior to anodizing. Electro-Chemical polishing functions by leveling the microscopic peaks and valleys of the substrate, thereby increasing specularity and reducing light scattering. The rate of attack is dependent of the physical characteristics (height, depth, and width) of the microscopic structures that constitute the surface finish. To prepare the sample, mechanical polishing such as buffing or grinding is typically required before etching. This type of mechanical polishing produces random microscopic structures at varying depths and widths, thus the electropolishing parameters are determined in an ad hoc basis. Alternatively, single point diamond turning offers excellent repeatability and highly specific control of substrate polishing parameters. While polishing, the diamond tool leaves behind an associated tool mark, which is related to the diamond tool geometry and machining parameters. Machine parameters such as tool cutting depth, speed and step over can be changed in situ, thus providing control of the spatial frequency of the microscopic structures characteristic of the surface topography of the substrate. By combining single point diamond turning with subsequent electro-chemical etching, ultra smooth polishing of both rotationally symmetric and free form mirrors and molds is possible. Additionally, machining parameters can be set to optimize post polishing for increased surface quality and reduced processing times. In this work, we present a study of substrate surface finish based on diamond turning tool mark spatial frequency with subsequent electro-chemical polishing.
{"title":"Quantification of microscopic surface features of single point diamond turned optics with subsequent chemical polishing","authors":"Nelson Cardenas, Matthew Kyrish, Daniel Taylor, M. Fraelich, Oscar M. Lechuga, R. Claytor, N. Claytor","doi":"10.1117/12.2080228","DOIUrl":"https://doi.org/10.1117/12.2080228","url":null,"abstract":"Electro-Chemical Polishing is routinely used in the anodizing industry to achieve specular surface finishes of various metals products prior to anodizing. Electro-Chemical polishing functions by leveling the microscopic peaks and valleys of the substrate, thereby increasing specularity and reducing light scattering. The rate of attack is dependent of the physical characteristics (height, depth, and width) of the microscopic structures that constitute the surface finish. To prepare the sample, mechanical polishing such as buffing or grinding is typically required before etching. This type of mechanical polishing produces random microscopic structures at varying depths and widths, thus the electropolishing parameters are determined in an ad hoc basis. Alternatively, single point diamond turning offers excellent repeatability and highly specific control of substrate polishing parameters. While polishing, the diamond tool leaves behind an associated tool mark, which is related to the diamond tool geometry and machining parameters. Machine parameters such as tool cutting depth, speed and step over can be changed in situ, thus providing control of the spatial frequency of the microscopic structures characteristic of the surface topography of the substrate. By combining single point diamond turning with subsequent electro-chemical etching, ultra smooth polishing of both rotationally symmetric and free form mirrors and molds is possible. Additionally, machining parameters can be set to optimize post polishing for increased surface quality and reduced processing times. In this work, we present a study of substrate surface finish based on diamond turning tool mark spatial frequency with subsequent electro-chemical polishing.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115774931","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}
C. Summitt, Sung-Yuen Wang, L. Johnson, Melissa Zaverton, Tao Ge, T. Milster, Y. Takashima
We have developed a hybrid lithography process necessary to fabricate a vertical optical coupler and an array of waveguide structures using the same buffer coat material on a single substrate. A virtual vernier scale built into the process enables precise alignment of both structures.
{"title":"Process optimization for a 3D optical coupler and waveguide fabrication on a single substrate using buffer coat material","authors":"C. Summitt, Sung-Yuen Wang, L. Johnson, Melissa Zaverton, Tao Ge, T. Milster, Y. Takashima","doi":"10.1117/12.2080425","DOIUrl":"https://doi.org/10.1117/12.2080425","url":null,"abstract":"We have developed a hybrid lithography process necessary to fabricate a vertical optical coupler and an array of waveguide structures using the same buffer coat material on a single substrate. A virtual vernier scale built into the process enables precise alignment of both structures.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128101037","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}
Y. Nishijima, A. Balčytis, R. Komatsu, T. Yamamura, G. Seniutinas, B. T. Wong, S. Juodkazis
Photo-thermal - to - electrical converter is demonstrated by using a commercial Peltier Bi-Te element with a hot contact made out of nanotextured Si (black-Si). Black-Si with colloidal Au nanoparticles is shown to further increase the efficiency of thermal-to-electrical conversion. Peculiarities of heat harvesting using black-Si with plasmonic Au nanoparticles at different gold densities are analyzed. Solar radiation absorption and electric field enhancement in plain and Au nanoparticle decorated black-Si was simulated using finite difference time domain (FDTD) method. Thermal conduction in nanotextured black-Si was explained using phonon Monte-Carlo simulations at the nanoscale. Strategies for creating larger thermal gradient on Peltier element using nanotextured light absorbers is discussed.
{"title":"Thermal to electrical energy converter based on black Si","authors":"Y. Nishijima, A. Balčytis, R. Komatsu, T. Yamamura, G. Seniutinas, B. T. Wong, S. Juodkazis","doi":"10.1117/12.2082403","DOIUrl":"https://doi.org/10.1117/12.2082403","url":null,"abstract":"Photo-thermal - to - electrical converter is demonstrated by using a commercial Peltier Bi-Te element with a hot contact made out of nanotextured Si (black-Si). Black-Si with colloidal Au nanoparticles is shown to further increase the efficiency of thermal-to-electrical conversion. Peculiarities of heat harvesting using black-Si with plasmonic Au nanoparticles at different gold densities are analyzed. Solar radiation absorption and electric field enhancement in plain and Au nanoparticle decorated black-Si was simulated using finite difference time domain (FDTD) method. Thermal conduction in nanotextured black-Si was explained using phonon Monte-Carlo simulations at the nanoscale. Strategies for creating larger thermal gradient on Peltier element using nanotextured light absorbers is discussed.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123786528","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}
Yu Zou, F. Villa, D. Bronzi, S. Tisa, A. Tosi, F. Zappa
Silicon Photomultipliers (SiPMs) are emerging single photon detectors used in many applications requiring large active area, photon-number resolving capability and immunity to magnetic fields. We present three families of analog SiPM fabricated in a reliable and cost-effective fully standard planar CMOS technology with a total photosensitive area of 1×1 mm2. These three families have different active areas with fill-factors (21%, 58.3%, 73.7%) comparable to those of commercial SiPM, which are developed in vertical (current flow) custom technologies. The peak photon detection efficiency in the near-UV tops at 38% (fill-factor included) comparable to commercial custom-process ones and dark count rate density is just a little higher than the best-in-class commercial analog SiPMs. Thanks to the CMOS processing, these new SiPMs can be integrated together with active components and electronics both within the microcell and on-chip, in order to act at the microcell level or to perform global pre-processing. We also report CMOS digital SiPMs in the same standard CMOS technology, based on microcells with digitalized processing, all integrated on-chip. This CMOS digital SiPMs has four 32×1 cells (128 microcells), each consisting of SPAD, active quenching circuit with adjustable dead time, digital control (to switch off noisy SPADs and readout position of detected photons), and fast trigger output signal. The achieved 20% fill-factor is still very good.
{"title":"Fully CMOS analog and digital SiPMs","authors":"Yu Zou, F. Villa, D. Bronzi, S. Tisa, A. Tosi, F. Zappa","doi":"10.1117/12.2077473","DOIUrl":"https://doi.org/10.1117/12.2077473","url":null,"abstract":"Silicon Photomultipliers (SiPMs) are emerging single photon detectors used in many applications requiring large active area, photon-number resolving capability and immunity to magnetic fields. We present three families of analog SiPM fabricated in a reliable and cost-effective fully standard planar CMOS technology with a total photosensitive area of 1×1 mm2. These three families have different active areas with fill-factors (21%, 58.3%, 73.7%) comparable to those of commercial SiPM, which are developed in vertical (current flow) custom technologies. The peak photon detection efficiency in the near-UV tops at 38% (fill-factor included) comparable to commercial custom-process ones and dark count rate density is just a little higher than the best-in-class commercial analog SiPMs. Thanks to the CMOS processing, these new SiPMs can be integrated together with active components and electronics both within the microcell and on-chip, in order to act at the microcell level or to perform global pre-processing. We also report CMOS digital SiPMs in the same standard CMOS technology, based on microcells with digitalized processing, all integrated on-chip. This CMOS digital SiPMs has four 32×1 cells (128 microcells), each consisting of SPAD, active quenching circuit with adjustable dead time, digital control (to switch off noisy SPADs and readout position of detected photons), and fast trigger output signal. The achieved 20% fill-factor is still very good.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127561548","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}
C. Holmes, L. Carpenter, J. Gates, C. Gawith, P. Smith
We demonstrate the fabrication of a mechanically robust planarised fibre-FHD optical composite. Fabrication is achieved through deposition and consolidation of optical grade silica soot on to both an optical fibre and planar substrate. The consolidated silica acts in joining the fibre and planar substrate both mechanically and optically. The concept lends itself to applications where long interaction lengths (order of tens of centimetres) and optical interaction via a planar waveguide are required, such as pump schemes, precision layup of fibre optics and hybrid fibre-planar devices. This paper considers the developments in fabrication process that enable component development.
{"title":"Planarized fiber-FHD optical composite","authors":"C. Holmes, L. Carpenter, J. Gates, C. Gawith, P. Smith","doi":"10.1117/12.2079481","DOIUrl":"https://doi.org/10.1117/12.2079481","url":null,"abstract":"We demonstrate the fabrication of a mechanically robust planarised fibre-FHD optical composite. Fabrication is achieved through deposition and consolidation of optical grade silica soot on to both an optical fibre and planar substrate. The consolidated silica acts in joining the fibre and planar substrate both mechanically and optically. The concept lends itself to applications where long interaction lengths (order of tens of centimetres) and optical interaction via a planar waveguide are required, such as pump schemes, precision layup of fibre optics and hybrid fibre-planar devices. This paper considers the developments in fabrication process that enable component development.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134487103","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}
Bilali Muhutijiang, Keqiang Qiu, Yanchang Zheng, Xiaolong Jiang, Yilin Hong
Broadband gold-coated grating (BGCG) is one of the key elements of large pulse compression systems. Compared with other pulse compression grating (PCG), BGCG have the advantages of simple structure and low cost etc. More importantly, this kind of grating can get high diffraction efficiency within a broadband range (usually 200 nm or more). In this paper the authors report a process for fabrication of sine-top BGCG. When gratings are intended for use with high-power lasers, their laser-damage threshold has an importance equal to that of the diffraction efficiency. These gratings fabricated by this method differ from conventional metal-on-photoresist PCGs in that the gratings patterns are generated by etching the fused silica substrate directly. This can improve the laser damage threshold. The groove depth and duty cycle of the photoresist mask were controlled by changing photoresist thickness and adjusting exposure and development time. The duty cycle of the fused silica grating was further corrected by oxygen plasma etching. Using this method, high efficiency sine-top BGCGs with line densities of 1740 lines /mm have been achieved, this paper has a good reference value to the further fabrication of larger aperture gold-coated PCG.
{"title":"Fabrication of sine-top broadband gold-coated gratings","authors":"Bilali Muhutijiang, Keqiang Qiu, Yanchang Zheng, Xiaolong Jiang, Yilin Hong","doi":"10.1117/12.2075013","DOIUrl":"https://doi.org/10.1117/12.2075013","url":null,"abstract":"Broadband gold-coated grating (BGCG) is one of the key elements of large pulse compression systems. Compared with other pulse compression grating (PCG), BGCG have the advantages of simple structure and low cost etc. More importantly, this kind of grating can get high diffraction efficiency within a broadband range (usually 200 nm or more). In this paper the authors report a process for fabrication of sine-top BGCG. When gratings are intended for use with high-power lasers, their laser-damage threshold has an importance equal to that of the diffraction efficiency. These gratings fabricated by this method differ from conventional metal-on-photoresist PCGs in that the gratings patterns are generated by etching the fused silica substrate directly. This can improve the laser damage threshold. The groove depth and duty cycle of the photoresist mask were controlled by changing photoresist thickness and adjusting exposure and development time. The duty cycle of the fused silica grating was further corrected by oxygen plasma etching. Using this method, high efficiency sine-top BGCGs with line densities of 1740 lines /mm have been achieved, this paper has a good reference value to the further fabrication of larger aperture gold-coated PCG.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125355679","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}
R. Welser, A. Sood, S. R. Tatavarti, A. Wibowo, D. Wilt, A. Howard
High-voltage InGaAs quantum well solar cells have been demonstrated in a thin-film format, utilizing structures that employ advanced band gap engineering to suppress non-radiative recombination and expose the limiting radiative component of the diode current. In particular, multiple InGaAs quantum well structures fabricated via epitaxial lift-off exhibit one-sun open circuit voltages as high as 1.05 V. The dark diode characteristics of these high-voltage III-V photovoltaic devices are compared to the radiative current calculated from the measured external quantum efficiency using a generalized detailed balance model specifically adapted for optically-thin absorber structures. The fitted n=1 component of the diode current is found to match the calculated radiative dark current when assuming negligible photon recycling, suggesting this thin-film multiple quantum well structure is operating close to the radiative limit.
{"title":"Radiative dark current in optically thin III-V photovoltaic devices","authors":"R. Welser, A. Sood, S. R. Tatavarti, A. Wibowo, D. Wilt, A. Howard","doi":"10.1117/12.2185571","DOIUrl":"https://doi.org/10.1117/12.2185571","url":null,"abstract":"High-voltage InGaAs quantum well solar cells have been demonstrated in a thin-film format, utilizing structures that employ advanced band gap engineering to suppress non-radiative recombination and expose the limiting radiative component of the diode current. In particular, multiple InGaAs quantum well structures fabricated via epitaxial lift-off exhibit one-sun open circuit voltages as high as 1.05 V. The dark diode characteristics of these high-voltage III-V photovoltaic devices are compared to the radiative current calculated from the measured external quantum efficiency using a generalized detailed balance model specifically adapted for optically-thin absorber structures. The fitted n=1 component of the diode current is found to match the calculated radiative dark current when assuming negligible photon recycling, suggesting this thin-film multiple quantum well structure is operating close to the radiative limit.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129650769","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}
M. da Silva, S. Almosni, C. Cornet, A. Létoublon, C. Levallois, P. Râle, L. Lombez, J. Guillemoles, O. Durand
GaAsPN semiconductors are promising material for the elaboration of high efficiencies tandem solar cells on silicon substrates. GaAsPN diluted nitride alloy is studied as the top junction material due to its perfect lattice matching with the Si substrate and its ideal bandgap energy allowing a perfect current matching with the Si bottom cell. We review our recent progress in materials development of the GaAsPN alloy and our recent studies of some of the different building blocks toward the elaboration of a PIN solar cell. A lattice matched (with a GaP(001) substrate, as a first step toward the elaboration on a Si substrate) 1μm-thick GaAsPN alloy has been grown by MBE. After a post-growth annealing step, this alloy displays a strong absorption around 1.8-1.9 eV, and efficient photoluminescence at room temperature suitable for the elaboration of the targeted solar cell top junction. Early stage GaAsPN PIN solar cells prototypes have been grown on GaP (001) substrates, with 2 different absorber thicknesses (1μm and 0.3μm). The external quantum efficiencies and the I-V curves show that carriers have been extracted from the GaAsPN alloy absorbers, with an open-circuit voltage of 1.18 V, while displaying low short circuit currents meaning that the GaAsPN structural properties needs a further optimization. A better carrier extraction has been observed with the absorber displaying the smallest thickness, which is coherent with a low carriers diffusion length in our GaAsPN compound. Considering all the pathways for improvement, the efficiency obtained under AM1.5G is however promising.
{"title":"GaAsPN-based PIN solar cells MBE-grown on GaP substrates: toward the III-V/Si tandem solar cell","authors":"M. da Silva, S. Almosni, C. Cornet, A. Létoublon, C. Levallois, P. Râle, L. Lombez, J. Guillemoles, O. Durand","doi":"10.1117/12.2081376","DOIUrl":"https://doi.org/10.1117/12.2081376","url":null,"abstract":"GaAsPN semiconductors are promising material for the elaboration of high efficiencies tandem solar cells on silicon substrates. GaAsPN diluted nitride alloy is studied as the top junction material due to its perfect lattice matching with the Si substrate and its ideal bandgap energy allowing a perfect current matching with the Si bottom cell. We review our recent progress in materials development of the GaAsPN alloy and our recent studies of some of the different building blocks toward the elaboration of a PIN solar cell. A lattice matched (with a GaP(001) substrate, as a first step toward the elaboration on a Si substrate) 1μm-thick GaAsPN alloy has been grown by MBE. After a post-growth annealing step, this alloy displays a strong absorption around 1.8-1.9 eV, and efficient photoluminescence at room temperature suitable for the elaboration of the targeted solar cell top junction. Early stage GaAsPN PIN solar cells prototypes have been grown on GaP (001) substrates, with 2 different absorber thicknesses (1μm and 0.3μm). The external quantum efficiencies and the I-V curves show that carriers have been extracted from the GaAsPN alloy absorbers, with an open-circuit voltage of 1.18 V, while displaying low short circuit currents meaning that the GaAsPN structural properties needs a further optimization. A better carrier extraction has been observed with the absorber displaying the smallest thickness, which is coherent with a low carriers diffusion length in our GaAsPN compound. Considering all the pathways for improvement, the efficiency obtained under AM1.5G is however promising.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133695312","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}
A. Walker, O. Höhn, D. Micha, L. Wagner, H. Helmers, A. Bett, F. Dimroth
Single junction photovoltaic devices composed of direct bandgap III-V semiconductors such as GaAs can exploit the effects of photon recycling to achieve record-high open circuit voltages. Modeling such devices yields insight into the design and material criteria required to achieve high efficiencies. For a GaAs cell to reach 28 % efficiency without a substrate, the Shockley-Read-Hall (SRH) lifetimes of the electrons and holes must be longer than 3 s and 100 ns respectively in a 2 μm thin active region coupled to a very high reflective (>99%) rear-side mirror. The model is generalized to account for luminescence coupling in tandem devices, which yields direct insight into the top cell’s non-radiative lifetimes. A heavily current mismatched GaAs/GaAs tandem device is simulated and measured experimentally as a function of concentration between 3 and 100 suns. The luminescence coupling increases from 14 % to 33 % experimentally, whereas the model requires an increasing SRH lifetime for both electrons and holes to explain these experimental results. However, intermediate absorbing GaAs layers between the two sub-cells may also increasingly contribute to the luminescence coupling as a function of concentration.
{"title":"Impact of photon recycling and luminescence coupling in III-V photovoltaic devices","authors":"A. Walker, O. Höhn, D. Micha, L. Wagner, H. Helmers, A. Bett, F. Dimroth","doi":"10.1117/12.2084508","DOIUrl":"https://doi.org/10.1117/12.2084508","url":null,"abstract":"Single junction photovoltaic devices composed of direct bandgap III-V semiconductors such as GaAs can exploit the effects of photon recycling to achieve record-high open circuit voltages. Modeling such devices yields insight into the design and material criteria required to achieve high efficiencies. For a GaAs cell to reach 28 % efficiency without a substrate, the Shockley-Read-Hall (SRH) lifetimes of the electrons and holes must be longer than 3 s and 100 ns respectively in a 2 μm thin active region coupled to a very high reflective (>99%) rear-side mirror. The model is generalized to account for luminescence coupling in tandem devices, which yields direct insight into the top cell’s non-radiative lifetimes. A heavily current mismatched GaAs/GaAs tandem device is simulated and measured experimentally as a function of concentration between 3 and 100 suns. The luminescence coupling increases from 14 % to 33 % experimentally, whereas the model requires an increasing SRH lifetime for both electrons and holes to explain these experimental results. However, intermediate absorbing GaAs layers between the two sub-cells may also increasingly contribute to the luminescence coupling as a function of concentration.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133095557","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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