Investigation of the Electrical Properties of Grain Boundaries in (AgxCu1-x)(InyGa1-y)Se2

Alloying Cu(InGa)Se
₂
(CIGS) with Ag(InGa)Se
₂
results in thin films that are more defect tolerant and can improve device performance compared with pure CIGS. In this study scanning microwave impedance microscopy (sMIM) and time of flight secondary ion mass spectrometry (TOF-SIMS) were used to investigate the electrical characteristics of grain boundaries in ACIGS. Two films were deposited by a three stage co-evaporation technique. sMIM measurements revealed Sample A to have high variation in electrical properties between grains and grain boundaries while Sample B was uniform across the surface. TOF-SIMS measurements found Sample A to have low oxygen inclusion while Sample B had increased oxygen at the grain boundaries. It is theorized that oxygen atoms are filling V
_Se
at grain boundaries and passivating the electronic behavior.