Direct evidence of a Cu(In,Ga)3Se5 phase in a bulk, high-efficiency Cu(In,Ga)Se2 device using atom probe tomography

This paper will descuss the findings of an ordered vacancy compound (OVC) phase, Cu(In,Ga)₃Se₅ (135 phase), that exists deep into the bulk of a high-efficiency CIGSe absorber as determined by atom probe tomography (APT). To date, literature has shown that absorbers grown with the three-step process exhibit the 135 phase only within the first few nanometers from the CdS/CIGSe interface. In this contribution, we have found a small volume (100 nm × 100 nm × 300 nm) of the 135 phase to exist about 400 nm into the absorber. The paper will discuss possibly why the phase was found by APT and not by other characterization techniques.