Proton irradiation damage in Zn and Cd doped InP
In an attempt to better understand the superior radiation resistance of InP solar cells, 2 MeV proton irradiation damage was studied in Zn and Cd doped InP Schottky diodes. The damage was analyzed using the capacitance/voltage technique to study carrier loss, and using DLTS to study the irradiation induced deep levels. The carrier removal rate was found to be identical in both Zn and Cd doped InP. The DLTS spectrum of Cd doped InP was studied in detail for the first time: it was identical to the spectrum of comparably Zn doped InP. Two irradiation induced deep levels dominated the DLTS spectra in Cd and Zn doped InP, H3 at E{sub v} + 0.28 eV and H5 at E{sub v} + 0.57 eV. The defect H4 at E{sub v} + 0.37 eV was not observed in the heavily Zn or Cd doped samples, but was observed in the heavily Zn or Cd doped samples, but was observed in lightly Zn doped samples. This effect is related to the dependence of the annealing rate of H4 on dopant concentration and type. The introduction rate of H3 was identical in both materials, but the introduction rate of H5 was lower in Cd doped InP. This effect is attributed to the slower diffusion rate of Cd and its effect on the formation of H5, a defect-dopant complex. The annealing rates of the defects were higher in Cd doped InP than in Zn doped InP. A model is suggested in which the defects H3 and H4 are eliminated at a dopant interstitial created during irradiation. The slower diffusion of Cd leads to slower elimination of the interstitial at sinks. The higher interstitial concentration results in an increased defect annealing rate. The slower diffusion rate of Cd inhibits the formation of H5, but its concentration grows rapidly on annealing. After annealing the concentration of H5 was nearly the same in comparably Zn and Cd doped InP. The enhanced annealing rates of H3 and H4, and the reduced formation rate of H5 make Cd doped InP more radiation resistant than Zn doped InP.
- Research Organization:
- Case Western Reserve Univ., Cleveland, OH (United States)
- OSTI ID:
- 106972
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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