Study Of Defects In Proton Irradiated GaAs/AlGaAs Solar Cells

The properties of GaAs/AlGaAs solar cells irradiated with different energy protons have been studied.Current-voltage(IV),deep level transient spectroscopy (DLTS) and capacitance-voltage(CV) measurements were carried out to study the degradation of solar cells caused by protons irradiation.The experimental results of DLTS measurement were compared with the stopping and range of ions in matter (SRIM) simulation.The following is the results:1.Current-voltage(IV) measurement showed that the worst degradation was found in the cells irradiated by 100keV protons,while for 40keV and 4MeV protons, the degradation is better than that of 70,100,170keV protons.For protons with same energy but different flux,the higher flux,the more degradation.The SRIM simulation shows the profile of vacancy introduced by protons.2.DLTS measurement is used to measure deep levels defects in depletion region of PN junction or Schottky barrier.From typical DLTS curve,the energy level, concentration,and capture cross section of defects can be obtained.The results of DLTS measurements show that the defects caused by 100keV are highest.The signal of 40keV,4MeV proton irradiation samples are very small.This can be explained from SRIM simulation.3.The distribution of traps in the proton implantation sample could be dependant on the depth.In order to deduce the defect distribution in the depletion region, traditional calculation formula of DLTS defect concentration has been modified. Different pulse and bias voltage were used in DLTS measurement.DLTS measurement showed good agreement with that of the SRIM simulation.4.The source of defects are studied.