Detection of Nonradiative Recombination Centers in GaPN (N:0.105%) by Below‐Gap Excitation Light

Investigation on cascade photo-excitation via intermediate band (IB) is promising for improving the efficiency of IB-type solar cells (IBSCs). Increasing nitrogen (N) concentration in GaP changes an ensemble of discrete N-N pair levels to form the IB as well as introducing defect levels acting as nonradiative recombination (NRR) centers. In continuation of detecting NRR centers in GaP1-xNx (x>0.5%), a study is made for the lower N concentration region of 0.105% to understand an original formation of defect levels and their properties. Elimination of temperature quenching by immersing the sample into liquid nitrogen reveals a distribution of NRR centers inside the forbidden energy gap and the shift of Fermi energy depending on above-gap excitation (AGE) density. Profound understanding of IB and defects of GaP1-xNx leads to a proper optimization of IBSCs.