Thermoelectric (TE) thin films have promise for harvesting electrical energy from waste heat. We ... more Thermoelectric (TE) thin films have promise for harvesting electrical energy from waste heat. We demonstrate TE materials and thermocouples deposited by aqueous spray deposition on glass. The n-type material was CdO doped with Mn and Sn. Two p-type materials were investigated, namely PbS with co-growth of CdS and doped with Na and Na2CoO4. Seebeck coefficients, resistivity, and power generation for thermocouples were characterized.
Low-cost, light-weight, low-power, large-format, room-temperature, mid-wave infrared (MWIR) detec... more Low-cost, light-weight, low-power, large-format, room-temperature, mid-wave infrared (MWIR) detectors are needed for reduced-scale aircraft. An opportunity, suggested by direct-read X-radiography systems, is the use of thin film transistor (TFT) array as read-out integrated circuit (ROIC) for low-cost sensors deposited directly and unpatterned onto this ROIC. TFTs have already been thoroughly optimized for power, weight, large-format, and cost by the flat-panel-display industry. We present experimental investigation of aqueous-spray-deposited, mid-wave-IR, metal-chalcogenide heterojunction CdS/PbS photodiodes for this application. Measured responsivity, detectivity D*, and photoresponse spectra are reported.
ABSTRACT Deposition of high quality zinc sulfide (ZnS) thin film over a large area is required if... more ABSTRACT Deposition of high quality zinc sulfide (ZnS) thin film over a large area is required if it is to be effectively used in electroluminescent devices, solar cells, and other optoelectronic devices. Of all deposition techniques, chemical bath deposition (CBD) is the least costly technique that meets the above requirements. Recently it is found that the growth of ZnS film, of thickness less than 100 nm in a single dip, by CBD is facilitated by the use of ammonia and hydrazine as complexing agents. Here we report that the thickness of the deposited ZnS film can be increased if ammonium salt is used as a buffer. We also present an analytical study to explain our results and to further understand the ZnS growth process in CBD.
II-VI compounds are direct bandgap semiconductors with great potentials in optoelectronic applica... more II-VI compounds are direct bandgap semiconductors with great potentials in optoelectronic applications. Solar cells, where these materials are in greater demand, require a low cost production technology that will make the final product more affordable. Chemical bath deposition (CBD) a low cost growth technique capable of producing good quality thin film semiconductors over large area and at low temperature then
The performance of CdTe/CdS/TCO/glass structure which is generally used as a solar cell depends o... more The performance of CdTe/CdS/TCO/glass structure which is generally used as a solar cell depends on the impurities incorporated in the system before and after electrodeposition of CdTe thin films. In this report we present a detailed investigation of this structure using secondary ion mass spectrometry(SIMS), x-ray microanalysis, x-ray diffraction(XRD), and scanning electron microscopy(SEM) to identify those impurities. We also discuss
Thermoelectric (TE) thin films have promise for harvesting electrical energy from waste heat. We ... more Thermoelectric (TE) thin films have promise for harvesting electrical energy from waste heat. We demonstrate TE materials and thermocouples deposited by aqueous spray deposition on glass. The n-type material was CdO doped with Mn and Sn. Two p-type materials were investigated, namely PbS with co-growth of CdS and doped with Na and Na2CoO4. Seebeck coefficients, resistivity, and power generation for thermocouples were characterized.
Low-cost, light-weight, low-power, large-format, room-temperature, mid-wave infrared (MWIR) detec... more Low-cost, light-weight, low-power, large-format, room-temperature, mid-wave infrared (MWIR) detectors are needed for reduced-scale aircraft. An opportunity, suggested by direct-read X-radiography systems, is the use of thin film transistor (TFT) array as read-out integrated circuit (ROIC) for low-cost sensors deposited directly and unpatterned onto this ROIC. TFTs have already been thoroughly optimized for power, weight, large-format, and cost by the flat-panel-display industry. We present experimental investigation of aqueous-spray-deposited, mid-wave-IR, metal-chalcogenide heterojunction CdS/PbS photodiodes for this application. Measured responsivity, detectivity D*, and photoresponse spectra are reported.
ABSTRACT Deposition of high quality zinc sulfide (ZnS) thin film over a large area is required if... more ABSTRACT Deposition of high quality zinc sulfide (ZnS) thin film over a large area is required if it is to be effectively used in electroluminescent devices, solar cells, and other optoelectronic devices. Of all deposition techniques, chemical bath deposition (CBD) is the least costly technique that meets the above requirements. Recently it is found that the growth of ZnS film, of thickness less than 100 nm in a single dip, by CBD is facilitated by the use of ammonia and hydrazine as complexing agents. Here we report that the thickness of the deposited ZnS film can be increased if ammonium salt is used as a buffer. We also present an analytical study to explain our results and to further understand the ZnS growth process in CBD.
II-VI compounds are direct bandgap semiconductors with great potentials in optoelectronic applica... more II-VI compounds are direct bandgap semiconductors with great potentials in optoelectronic applications. Solar cells, where these materials are in greater demand, require a low cost production technology that will make the final product more affordable. Chemical bath deposition (CBD) a low cost growth technique capable of producing good quality thin film semiconductors over large area and at low temperature then
The performance of CdTe/CdS/TCO/glass structure which is generally used as a solar cell depends o... more The performance of CdTe/CdS/TCO/glass structure which is generally used as a solar cell depends on the impurities incorporated in the system before and after electrodeposition of CdTe thin films. In this report we present a detailed investigation of this structure using secondary ion mass spectrometry(SIMS), x-ray microanalysis, x-ray diffraction(XRD), and scanning electron microscopy(SEM) to identify those impurities. We also discuss
Uploads
Papers by Isaiah Oladeji