Pub Date : 2002-12-11DOI: 10.1109/COMMAD.2002.1237216
T. Nguyen, C. Musca, J. Dell, J. Antoszewski, L. Faraone
HgCdTe long-wavelength infrared (LWIR) photodiodes have been successfully fabricated using plasma induced junction formation. The performance of the devices were characterised through I-V measurements and analysed by modelling the dark current mechanisms which determine the I-V characteristic. Analytical models were used and a very close fit to the measured data at 80 K was achieved. The model included the effects of diffusion, trap-assisted tunnelling, band-to-band tunnelling, generation-recombination, and surface leakage current. The dark current modelling has identified material defects and non-ideal surface passivation as the factors limiting performance in HgCdTe LWIR photodiodes fabricated using plasma induced junction formation.
{"title":"Modelling of dark currents in LWIR HgCdTe photodiodes","authors":"T. Nguyen, C. Musca, J. Dell, J. Antoszewski, L. Faraone","doi":"10.1109/COMMAD.2002.1237216","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237216","url":null,"abstract":"HgCdTe long-wavelength infrared (LWIR) photodiodes have been successfully fabricated using plasma induced junction formation. The performance of the devices were characterised through I-V measurements and analysed by modelling the dark current mechanisms which determine the I-V characteristic. Analytical models were used and a very close fit to the measured data at 80 K was achieved. The model included the effects of diffusion, trap-assisted tunnelling, band-to-band tunnelling, generation-recombination, and surface leakage current. The dark current modelling has identified material defects and non-ideal surface passivation as the factors limiting performance in HgCdTe LWIR photodiodes fabricated using plasma induced junction formation.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"339 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132778971","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237278
Jiayi Huang, T.P. Chen, M. Tse
In this study, a novel technique, i.e. the direct-current current-voltage (DCIV) method is used to quantitatively examine the influence of nitrogen concentration in nitrided oxide on interface trap generation caused by DC and dynamic Fowler-Nordheim (FN) injections. For both DC and dynamic FN stresses, a power-law stress-time dependence of interface trap generation is always observed, and the increase of nitrogen concentration leads to a significant suppression of interface trap generation. For the dynamic stress, interface trap generation increases with frequency, but the interface trap generation at each frequency is reduced with a higher nitrogen concentration. A comparison of interface trap generation between DC and dynamic stresses and explanation for the difference are presented. The nitridation effect on the interface trap generation can be explained by the models based on either the rigid Si-N bonds at the interface or the nitrided oxide impediment to the damaging positive species such as H/sup +/ or holes.
{"title":"Study of influence of nitrogen concentration in nitrided oxide on interface trap generation","authors":"Jiayi Huang, T.P. Chen, M. Tse","doi":"10.1109/COMMAD.2002.1237278","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237278","url":null,"abstract":"In this study, a novel technique, i.e. the direct-current current-voltage (DCIV) method is used to quantitatively examine the influence of nitrogen concentration in nitrided oxide on interface trap generation caused by DC and dynamic Fowler-Nordheim (FN) injections. For both DC and dynamic FN stresses, a power-law stress-time dependence of interface trap generation is always observed, and the increase of nitrogen concentration leads to a significant suppression of interface trap generation. For the dynamic stress, interface trap generation increases with frequency, but the interface trap generation at each frequency is reduced with a higher nitrogen concentration. A comparison of interface trap generation between DC and dynamic stresses and explanation for the difference are presented. The nitridation effect on the interface trap generation can be explained by the models based on either the rigid Si-N bonds at the interface or the nitrided oxide impediment to the damaging positive species such as H/sup +/ or holes.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134187061","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237298
V. Coleman, P. Deenapanray, H. Tan, C. Jagadish
We have used deep level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements to study impurity free disordering (IFD) of p-type GaAs epitaxial layers grown by metal-organic chemical vapour deposition (MOCVD). Disordering was achieved using either an SiO/sub 2/ or native oxide layer of the same thickness. Samples, including an uncapped layer for reference, were annealed at 900/spl deg/C for 30 s under an Ar ambient. Impurity-free disordering resulted in an increase in the free hole concentration, with the effect being most pronounced when using the SiO/sub 2/ capping layer. DLTS measurements revealed a corresponding increase in the concentrations of both Cu- and Zn-related deep levels in disordered epilayers. The results presented here will be discussed in terms of the atomic relocation processes that take place during the nonequilibrium injection of excess gallium vacancies into the disordered p-type epilayers.
{"title":"Atomic relocation of fast diffusers in impurity-free disordered p-type GaAs","authors":"V. Coleman, P. Deenapanray, H. Tan, C. Jagadish","doi":"10.1109/COMMAD.2002.1237298","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237298","url":null,"abstract":"We have used deep level transient spectroscopy (DLTS) and capacitance-voltage (C-V) measurements to study impurity free disordering (IFD) of p-type GaAs epitaxial layers grown by metal-organic chemical vapour deposition (MOCVD). Disordering was achieved using either an SiO/sub 2/ or native oxide layer of the same thickness. Samples, including an uncapped layer for reference, were annealed at 900/spl deg/C for 30 s under an Ar ambient. Impurity-free disordering resulted in an increase in the free hole concentration, with the effect being most pronounced when using the SiO/sub 2/ capping layer. DLTS measurements revealed a corresponding increase in the concentrations of both Cu- and Zn-related deep levels in disordered epilayers. The results presented here will be discussed in terms of the atomic relocation processes that take place during the nonequilibrium injection of excess gallium vacancies into the disordered p-type epilayers.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133661314","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237285
S. Lee, G. Ditmer, N. Singh, C. Hodson, A. Goodyear, M. Cooke
Plasma enhanced chemical vapour deposition (PECVD) was used in the development of silica layers for use in planar lightwave circuit fabrication. These high-rate (>200 nm/min) processes are tailored specifically for the thick-film (5/spl sim/15 /spl mu/m) films required for these applications A GeH/sub 4/ addition to the process was used to deposit the core layer, controlling the core-clad refractive index (RI) difference in the range of 0.2%-1.65%. Undoped SiO/sub 2/ and Ge-doped SiO/sub 2/ films up to 10 /spl mu/m have been deposited on to 4" Si <100> wafers. The 'as deposited' and 'annealed' film properties: film uniformity, RI, RI uniformity and stress have been compared. The upper cladding layer in an optical planar waveguide is typically formed using boron and phosphorus doped films (BPSG) which provides the necessary reflow characteristics. Refractive index uniformity of /spl plusmn/0.0003 across 4" silicon wafers was achieved on all films after annealing. The core layer was shown to be capable of producing optical losses of <0.1 dB/cm when processed into a waveguide.
{"title":"Thick-film doped-oxide deposition processes for applications in planar lightwave circuit fabrication","authors":"S. Lee, G. Ditmer, N. Singh, C. Hodson, A. Goodyear, M. Cooke","doi":"10.1109/COMMAD.2002.1237285","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237285","url":null,"abstract":"Plasma enhanced chemical vapour deposition (PECVD) was used in the development of silica layers for use in planar lightwave circuit fabrication. These high-rate (>200 nm/min) processes are tailored specifically for the thick-film (5/spl sim/15 /spl mu/m) films required for these applications A GeH/sub 4/ addition to the process was used to deposit the core layer, controlling the core-clad refractive index (RI) difference in the range of 0.2%-1.65%. Undoped SiO/sub 2/ and Ge-doped SiO/sub 2/ films up to 10 /spl mu/m have been deposited on to 4\" Si <100> wafers. The 'as deposited' and 'annealed' film properties: film uniformity, RI, RI uniformity and stress have been compared. The upper cladding layer in an optical planar waveguide is typically formed using boron and phosphorus doped films (BPSG) which provides the necessary reflow characteristics. Refractive index uniformity of /spl plusmn/0.0003 across 4\" silicon wafers was achieved on all films after annealing. The core layer was shown to be capable of producing optical losses of <0.1 dB/cm when processed into a waveguide.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130118391","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237261
D. Debuf, R. Corkish
Semiconductor material characterization in terms of defect parameters is presently evaluated experimentally by applying the Shockley-Read-Hall (SRH) recombination time constant expression. A recent analytic solution to the SRH rate equations extended to differential rate equations for two multiple defect level systems, yields a solution derived without an approximation. In terms of material characterisation, this exact solution is shown to provide detailed information on multiple level depths in contrast to the existing theory, which relies on one dominant single level. Furthermore, for semiconductor samples known to be predominantly doped with one defect species, it is shown theoretically that the dominant decay is influenced by the other defect species present in the semiconductor sample.
{"title":"Recombination via discrete defect levels with application to semiconductor material characterisation","authors":"D. Debuf, R. Corkish","doi":"10.1109/COMMAD.2002.1237261","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237261","url":null,"abstract":"Semiconductor material characterization in terms of defect parameters is presently evaluated experimentally by applying the Shockley-Read-Hall (SRH) recombination time constant expression. A recent analytic solution to the SRH rate equations extended to differential rate equations for two multiple defect level systems, yields a solution derived without an approximation. In terms of material characterisation, this exact solution is shown to provide detailed information on multiple level depths in contrast to the existing theory, which relies on one dominant single level. Furthermore, for semiconductor samples known to be predominantly doped with one defect species, it is shown theoretically that the dominant decay is influenced by the other defect species present in the semiconductor sample.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"385 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116009567","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237241
L. Oberbeck, N. Curson, T. Hallam, M. Simmons, K. Goh, S. R. Schofield, F. Rueß, R. G. Clark
To optimise the fabrication process for a silicon based quantum computer the surface segregation/diffusion of phosphorus atoms in silicon is investigated on an atomic scale using scanning tunnelling microscopy (STM) after epitaxial silicon growth at 255 /spl deg/C and room temperature, respectively. The phosphorus atom in the Si(001) surface forms a silicon-phosphorus heterodimer identified as a bright zigzag feature in filled state STM images. Sample annealing, used to reduce the surface roughness and the defect density after silicon growth is shown to increase the density of phosphorus atoms at the surface. However, the density of phosphorus atoms can be limited to a few percent of the initial density if the phosphorus atoms are encapsulated in silicon at room temperature.
{"title":"Minimisation of P surface segregation during epitaxial silicon growth for the fabrication of a silicon-based quantum computer","authors":"L. Oberbeck, N. Curson, T. Hallam, M. Simmons, K. Goh, S. R. Schofield, F. Rueß, R. G. Clark","doi":"10.1109/COMMAD.2002.1237241","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237241","url":null,"abstract":"To optimise the fabrication process for a silicon based quantum computer the surface segregation/diffusion of phosphorus atoms in silicon is investigated on an atomic scale using scanning tunnelling microscopy (STM) after epitaxial silicon growth at 255 /spl deg/C and room temperature, respectively. The phosphorus atom in the Si(001) surface forms a silicon-phosphorus heterodimer identified as a bright zigzag feature in filled state STM images. Sample annealing, used to reduce the surface roughness and the defect density after silicon growth is shown to increase the density of phosphorus atoms at the surface. However, the density of phosphorus atoms can be limited to a few percent of the initial density if the phosphorus atoms are encapsulated in silicon at room temperature.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114411332","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237242
T. Trupke, J. Zhao, A. Wang, M. Green
An analytical relation between the internal- and the external luminescence quantum efficiency of textured silicon wafers is derived using a generalisation of Kirchhoff s law. We show that only a fraction of one third of internally generated photons can escape a textured 450 /spl mu/m thick silicon wafer even under the idealising assumption of negligible free carrier absorption, the major fraction of photons being reabsorbed by band-band-transitions. Surprisingly high external luminescence quantum efficiencies up to 0.6% at room temperature of silicon light emitting diodes have been published recently. From our theoretical model we can conclude that further significant improvements of the external luminescence quantum efficiency of silicon devices can be achieved by optimising the thickness of the devices, the texturing and the passivation of the surfaces texturing.
{"title":"Improving silicon light emitting devices using Kirchhoff's law","authors":"T. Trupke, J. Zhao, A. Wang, M. Green","doi":"10.1109/COMMAD.2002.1237242","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237242","url":null,"abstract":"An analytical relation between the internal- and the external luminescence quantum efficiency of textured silicon wafers is derived using a generalisation of Kirchhoff s law. We show that only a fraction of one third of internally generated photons can escape a textured 450 /spl mu/m thick silicon wafer even under the idealising assumption of negligible free carrier absorption, the major fraction of photons being reabsorbed by band-band-transitions. Surprisingly high external luminescence quantum efficiencies up to 0.6% at room temperature of silicon light emitting diodes have been published recently. From our theoretical model we can conclude that further significant improvements of the external luminescence quantum efficiency of silicon devices can be achieved by optimising the thickness of the devices, the texturing and the passivation of the surfaces texturing.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114913003","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237185
P. Arifin, Sugianto, E. Suprianto, N. Wendri, H. Sutanto, M. Budiman, M. Barmawi
Thin films Al/sub x/Ga/sub 1-x/N were grown on (0001) sapphire substrates by plasma assisted metal-organic chemical vapor deposition (PA-MOCVD). Plasma-cracked N/sub 2/, trimethylaluminum (TMAl) and trimethylgallium (TMGa) were used as nitrogen, aluminum and gallium sources, respectively. The results of energy dispersive X-ray (EDX) measurements performed at room temperature yielded the linear dependence of molar fraction of Al (x) on molar fraction of vapor phase of TMAl/(TMAl + TMGa). The dependence of the band gap energy on the molar fraction of Al (x) showed quadratic expression, E/sub g/ (x) = 3.35 + 1.55x + 1.3x/sup 2/ eV. Al/sub x/Ga/sub 1-x/N layers with x < 0.34 show n-type conduction with room temperature mobilities in the range of 5 to 10 cm/sup 2//V/spl middot/s, and electron concentrations of 9.0 /spl times/ 10/sup 16/ to 1.4 /spl times/ 10/sup 19/cm/sup -3/.
{"title":"Growth of Al/sub x/Ga/sub 1-x/N by plasma assisted MOCVD","authors":"P. Arifin, Sugianto, E. Suprianto, N. Wendri, H. Sutanto, M. Budiman, M. Barmawi","doi":"10.1109/COMMAD.2002.1237185","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237185","url":null,"abstract":"Thin films Al/sub x/Ga/sub 1-x/N were grown on (0001) sapphire substrates by plasma assisted metal-organic chemical vapor deposition (PA-MOCVD). Plasma-cracked N/sub 2/, trimethylaluminum (TMAl) and trimethylgallium (TMGa) were used as nitrogen, aluminum and gallium sources, respectively. The results of energy dispersive X-ray (EDX) measurements performed at room temperature yielded the linear dependence of molar fraction of Al (x) on molar fraction of vapor phase of TMAl/(TMAl + TMGa). The dependence of the band gap energy on the molar fraction of Al (x) showed quadratic expression, E/sub g/ (x) = 3.35 + 1.55x + 1.3x/sup 2/ eV. Al/sub x/Ga/sub 1-x/N layers with x < 0.34 show n-type conduction with room temperature mobilities in the range of 5 to 10 cm/sup 2//V/spl middot/s, and electron concentrations of 9.0 /spl times/ 10/sup 16/ to 1.4 /spl times/ 10/sup 19/cm/sup -3/.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123318927","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237182
J.M. Zanardi Ocampo, P. Vaccaro, S. Saravanan, K. Kubota, T. Aida
Optoelectronic devices based on lateral junctions are particularly interesting because carriers are injected perpendicular to both the optical cavity and the direction of quantum confinement (i.e. the epitaxial growth direction). An edge-emitting InGaAs/GaAs laser diode with a lateral p-n junction was fabricated by MBE on a patterned GaAs (311)A substrate. The injection current dependence of the multimode emission was studied. Experimental results revealed a gain spectrum that favors long-wavelength modes as injection current increases.
{"title":"Longitudinal mode behavior of a lateral-junction edge-emitting laser diode","authors":"J.M. Zanardi Ocampo, P. Vaccaro, S. Saravanan, K. Kubota, T. Aida","doi":"10.1109/COMMAD.2002.1237182","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237182","url":null,"abstract":"Optoelectronic devices based on lateral junctions are particularly interesting because carriers are injected perpendicular to both the optical cavity and the direction of quantum confinement (i.e. the epitaxial growth direction). An edge-emitting InGaAs/GaAs laser diode with a lateral p-n junction was fabricated by MBE on a patterned GaAs (311)A substrate. The injection current dependence of the multimode emission was studied. Experimental results revealed a gain spectrum that favors long-wavelength modes as injection current increases.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114755807","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 : 2002-12-11DOI: 10.1109/COMMAD.2002.1237302
B. Lough, S. P. Lee, Z. Dou, R. Lewis, C. Zhang
We report our recent experimental and numerical investigation into the thermal and electrical transport in GaAs-AlGaAs semiconductor multilayer structures. Electrical and thermal conduction measurements were performed on multilayer structures to determine the temperature gradient across the sample. AuGe was used for top contact metallisation, and an InGa eutectic for bottom substrate contact. Metallisation contacts were also grown directly onto the substrate in order to compare results with and without the device included. By using a variable load resistor connected in series with the device, we can accurately determine the current-voltage characteristics of the device. Thus the power input can be obtained. The temperature distribution on the top and bottom substrate was measured with micro thermocouples. Since the cooling device is grown on an n-type semiconductor substrate the effects of joule heating in the substrate had to be considered. Treating the substrate as bulk material and calculating joule heating showed that this effect is negligible. Comparing experimental measurements of the device and of the substrate alone support this. The experimental I-V characteristics of the device differ significantly in shape from theoretical I-V characteristics. This may be due to that fact that space-charge effects are not included in the currently accepted model (Richardson's equation). Due to the small size of the devices and therefore very large electric fields, this effect may be important. Work is currently being carried out to modify the model. The devices studied so far have been made from undoped GaAs-AI/sub 0.07/Ga/sub 0.03/As heterostructures. For large cooling power it is a requirement that the conduction band of the layers be close to the Fermi level.
{"title":"Thermal and electrical characteristics of a multilayer thermionic device","authors":"B. Lough, S. P. Lee, Z. Dou, R. Lewis, C. Zhang","doi":"10.1109/COMMAD.2002.1237302","DOIUrl":"https://doi.org/10.1109/COMMAD.2002.1237302","url":null,"abstract":"We report our recent experimental and numerical investigation into the thermal and electrical transport in GaAs-AlGaAs semiconductor multilayer structures. Electrical and thermal conduction measurements were performed on multilayer structures to determine the temperature gradient across the sample. AuGe was used for top contact metallisation, and an InGa eutectic for bottom substrate contact. Metallisation contacts were also grown directly onto the substrate in order to compare results with and without the device included. By using a variable load resistor connected in series with the device, we can accurately determine the current-voltage characteristics of the device. Thus the power input can be obtained. The temperature distribution on the top and bottom substrate was measured with micro thermocouples. Since the cooling device is grown on an n-type semiconductor substrate the effects of joule heating in the substrate had to be considered. Treating the substrate as bulk material and calculating joule heating showed that this effect is negligible. Comparing experimental measurements of the device and of the substrate alone support this. The experimental I-V characteristics of the device differ significantly in shape from theoretical I-V characteristics. This may be due to that fact that space-charge effects are not included in the currently accepted model (Richardson's equation). Due to the small size of the devices and therefore very large electric fields, this effect may be important. Work is currently being carried out to modify the model. The devices studied so far have been made from undoped GaAs-AI/sub 0.07/Ga/sub 0.03/As heterostructures. For large cooling power it is a requirement that the conduction band of the layers be close to the Fermi level.","PeriodicalId":129668,"journal":{"name":"2002 Conference on Optoelectronic and Microelectronic Materials and Devices. COMMAD 2002. Proceedings (Cat. No.02EX601)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122742842","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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