On the Contribution of Bulk Defects on Charge Pumping Current

Frequency-dependent charge pumping (CP) (FD-CP) has emerged as a popular technique for studying the spatial and energetic distribution of defect centers in advanced high-k gate stacks. However, conflicting interpretations of the CP frequency-defect depth relationship has led to controversial and inconsistent findings between various groups. A key assumption is that most, if not all, bulk defect trapping/detrapping contributes to the CP current. In this paper, we show, experimentally using two independent measurements, that there is a large discrepancy between the total amount of bulk defect trapping/detrapping that occurs and the actual CP contribution due to these defects. We argue that the CP current due to bulk defects depends heavily upon the specific device geometry/technology, the minority-carrier lifetime, and FD-CP´s general inability to function as a defect profiling tool.