Sub-Band Gap Absoprtion in As and P Doped CdTe

Group-V doping in Cd-rich composition shows the promise of maximizing hole concentration while preserving lifetime in CdTe solar cells. Previously we demonstrated CdTe with hole doping >1017cm−3 and bulk lifetime >30 ns. However, Hall effect measurements of samples under exposure to light suggest the formation of metastable light induced defects. Here, we report early attempts to isolate and characterize this defect by means of spectrophotometry. We observe a narrowing of optical bandgap for samples with hole concentration >1017cm−3 as well as band tailing. Isolation of energy threshold of the defect via photoconductivity measurements are ongoing.