LeTID-affected Cells from a Utility-scale Photovoltaic System Characterized by Deep Level Transient Spectroscopy

作者：Steve Johnston, Chuanxiao Xiao, Michael G. Deceglie, E. Ashley Gaulding, Chun‐Sheng Jiang, Harvey Guthrey, Dana B. Kern, George F. Kroeger, Mowafak Al‐Jassim, Ingrid L. Repins · 年份：2021 · DOI：10.1109/pvsc43889.2021.9518401 · 被引用次数：4 · 研究领域：Silicon and Solar Cell Technologies、Thin-Film Transistor Technologies、Integrated Circuits and Semiconductor Failure Analysis

Photovoltaic modules from a utility-scale field experienced power loss by light- and elevated temperature-induced degradation (LeTID). Samples of one of the affected monocrystalline silicon cells were cored and extracted from the module packaging and encapsulation. One of the cell fragments was processed using a regeneration cycle of applying short-circuit-rated current in forward bias at 85°C for 2 weeks, while the other fragment was kept in its outdoor-degraded LeTID state. Both samples were scribed to form 2-mm diameter isolated areas using a femtosecond-pulse-width laser micromachining system. Both isolated areas contained front grid line segments which were wire bonded to larger contact pads, and the samples were probed in a cryostat linked to a deep-level transient spectroscopy (DLTS) system. Using DLTS, a majority-carrier, hole-trap defect was detected on each sample with an activation energy of 0.42 eV. The LeTID-degraded sample, however, had a larger signal corresponding to a trap density of 1.1x1013cm-3, which was about five times larger than the 2.1x1012cm-3trap density of the regenerated sample.