Radiation Hardness Analysis of InAsXP1-X/InP Multiquantum Well Solar Cells Structures for Space Applications

We have presented the results of the deep level transient spectroscopy (DLTS) study of the electron-radiation-induced defects in n-type InAs_xP_1-x/InP MQWs solar cell structures. Irradiation of CBE grown n-type InAs_xP_1-x/InP by 1 MeV electron with a dose of 3times10¹⁶ cm^-2 results in the appearance of a dominant electron emitting level E1, in the upper half of the band gap. The level E1 shows striking behavior during room temperature storage. It was found to completely anneal out with storage at room temperature with no change in other majority carrier levels. Detailed characteristics of these levels including thermal emission rates, carrier activation energies, and capture cross-sections have been determined. No any other defect has been observed in electron-irradiated n-type InAs_xP_1-x/InP MQWs solar cell structures, which contrasts to conventional n-InP solar cell counterparts (structures without QWs). This reveals that introduction of QWs in the intrinsic region of p-i-n structures enhances significantly the device radiation tolerance well beyond what has been thus far reported for conventional Si or III-V semiconductor-based solar cells