Detection of Nonradiative Recombination Centers in GaPN (N:0.105%) by Below‐Gap Excitation Light. Issue 2 (15th October 2019)

• Record Type: Journal Article
• Authors: Ferdous, Sanjida; Kamata, Norihiko; Yagi, Shuhei; Yaguchi, Hiroyuki
• Other Names: Tanaka Masaaki guestEditor.; Sugiyama Masakazu guestEditor.; Fujii Takuro guestEditor.; Ohya Shinobu guestEditor.
• Is Part Of: Physica status solidi. Volume 257:Issue 2(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-10-15
• Subjects: below-gap excitation -- defect level -- GaPN -- intermediate band -- nonradiative recombination; Solid state physics -- Periodicals; Solids -- Periodicals; Atomic structure -- Periodicals; 530.41
• DOI: 10.1002/pssb.201900377
• Languages: English
• ISSNs: 0370-1972

Abstract

Abstract : 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− x N x ( 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− x N x leads to a proper optimization of IBSCs. Abstract : The two‐wavelength excited photoluminescence (TWEPL) method reveals the presence of nonradiative recombination (NRR) centers in GaPN (N:0.105%). Different contribution of one and two‐level models explains the energy dependence of below‐gap excitation (BGE). The shift of Fermi‐energy in the mid‐gap level according to above‐gap excitation (AGE) photon number density plays an important role in the interpretation of NRR processes, which must be minimized for improving intermediate band solar cells (IBSCs).