Power and temperature dependent Photoluminescence of CuInSe₂ on N-polar GaN

Phoebe Nicole Perez^1*, Cheng-Chang Yu¹, Cheng-Hung Shih¹, Zhen-Chi Yang¹, Ikai Lo¹, Der-Jun Jang¹

¹Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan

* Presenter:Phoebe Nicole Perez, email:phoebeperez@g-mail.nsysu.edu.tw

This paper investigated the power and temperature dependent photoluminescence (PL) of epitaxially grown In-rich CuInSe₂ (CIS) and Cu-rich CuInSe₂ deposited on N-polar GaN. The Cu-rich CIS/GaN has PL emissions characterized by two donor-acceptor pair peaks at 0.97 eV and 0.94 eV, phonon replica at 0.86 eV and an excitonic peak at 1.03 eV. In contrast, In-rich CIS/GaN has broader and redshifted PL emission characterized by a multiplet peak centered at 0.92 eV and an excitonic peak at 1.08 eV. As the excitation power was increased, the total number of excitons increased instigating the increase in PL intensity of both samples. The power coefficients obtained confirmed the assignment of the peaks and indicated the type of exciton. The PL intensity of both samples decreased as the temperature was increased from 14 to 300 K due to the thermal ionization between atoms. To further determine the origin of the peaks, the carrier activation energies were extracted. The acquired activation energies agree with assignment of the peaks and were found to be higher than those previously reported. The identification of the PL emission source and nature of the transitions of both samples gives further insight on the incorporation of CIS with III-nitride materials.

Keywords: Photoluminescence, Copper indium diselenide, Gallium nitride, Solar cell absorber