The problem of increasing efficiency, reliability and radiation resistance
of solar cells based on AlGaAs/GaAs heterostructures can be solved by using
an internal Bragg reflector. The Bragg reflector as a back surface reflect
or and as a back surface potential barrier which allows to conserve the hig
h photosensitivity in the long- and middle-wavelength parts of the spectrum
after electron and proton irradiation. The effect of base doping and base
thickness on the radiation resistance of AlGaAs/GaAs solar cells with the i
nternal Bragg reflector has been investigated. Concentrator solar cells eff
iciency and related parameters before and after 3 MeV electron irradiation
at the fluence up to 3 x 10(15) cm(-2) are represented. A base doping level
of 1 x 10(15) cm(-3) and base thickness in the range 1.1-1.6 mum give an E
OL AM0 efficiency of 15.8% (BOL-22%) at 30 Suns concentration after exposur
e to 1 x 10(15) cm(-2) electron fluence. This EOL efficiency is among the h
ighest reported for GaAs single-junction concentrator cells under AM0 condi
tions, Making the base doping level lower and the base thinner allows retai
ning a j(EOL)j(BOL) ratio of 0.96 upon exposure up to 3 x 10(15)e/cm(2) 3 M
eV electron fluence. These results are additionally supported by the modeli
ng calculations of the relative damage coefficient. (C) 2001 Elsevier Scien
ce B.V. All rights reserved.