Growth and characterization of indium rich indium-gallium-nitride solar cell epitaxial structures by metal organic chemical vapor deposition

Çakmak, Hüseyin
The purpose of this study is to develop a technology for indium (In) rich indium gallium nitride (InGaN) solar cell epitaxial structures through metal organic chemical vapor deposition (MOCVD) method. InxGa1-xN solar cell structures have potential to cover 90% of the solar spectrum by varying In composition in the active region of the solar cell, where bandgaps of indium nitride (InN) and gallium nitride (GaN) are 0.7 eV and 3.4 eV, respectively. Photovoltaic devices that have a bandgap larger than 2.0 eV gather great interest since half of the available photons in the solar spectrum belongs there. However, only limited success has been achieved to increase the amount of In incorporation into InGaN epitaxial structures. This thesis is focused on the epitaxial growth of In rich InGaN epitaxial structures. These InGaN structures were grown on double side polished (DSP) c-plane sapphire substrates using MOCVD and then utilized for solar cells. Solar cell device characterizations were carried out after standart microfabrication procedures. X-Ray diffraction (XRD), Hall-Effect Measurements and absorption measurements have been done to investigate material properties first. Afterwards then the current voltage (I-V) characterizations were performed to investigate solar cell device performance. XRD measurements revealed that both GaN and InGaN epitaxial structures have high crystal quality, where full width at half maximum (FWHM) values of around 300 arcsec and 400 arsec for GaN and InGaN epilayers were obtained, respectively. In content was found to increase light absorption. Highest photovoltaic conversion of 0.66% was achieved for In0,16GaN films under a standard solar simulator with one-sun air mass (AM) 1.5 global light source ( 100mW/cm2) at room temperature. The solar simulator was calibrated with a standard solar cell before measurements. There is a increase on light absorption with increasing indium content in epitaxial structures. The best efficiency that was reached is 0.66% under air mass (AM) 1.5 global light source.


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Citation Formats
H. Çakmak, “Growth and characterization of indium rich indium-gallium-nitride solar cell epitaxial structures by metal organic chemical vapor deposition,” M.S. - Master of Science, Middle East Technical University, 2012.