The large-area One-per-wafer ZTJ and ZTJM solar cells from Emcore

The One-per-wafer denotes a single cell design for a large-area cell on a 100-mm diameter (4”) Ge wafer. As a result, the total area of this cell is on the order of ~60cm², which is twice as large as most conventional two-per-wafer solar cells. The silicon bypass diode design for the One-per-wafer cell has successfully passed electrical screening after forward bias, reverse bias and electrical cycling tests. The ZTJM solar cell incorporates a monolithically integrated GaAs bypass diode, which has been redesigned for significantly improved Electrostatic Discharge (ESD) resistance, exhibiting no change in dark current-voltage (DIV) characteristics after 10 normal (64A, 1.8 μs) or 10 inverted gradient (30A, 100 μs) ESD pulses. Pilot production results show a median bare-cell AM0 conversion efficiency of 29.2% for the One-per-wafer design and 29.1% for the ZTJM.