Optical properties of electron irradiation induced defects in InP

Abstract

The optical properties of deep hole traps H 4 and H 5 in p type and of the deep electron trap E 11 in n type InP, introduced by electron irradiation, have been studied using deep level optical spectroscopy. Comparison of the optical threshold with the thermal activation energy of H 5 level shows that it is highly relaxed with a Frank-Condon shift d Fc = 0.45 eV. The electron level E 11 is weakly relaxed and its optical cross section σ 0 is well accounted for by transitions to the Γ 6c minimum. The optical absorption σ p 0 associated to level H 4 shows two successive onsets at hν = 0.5 and hν = 1.2 eV which can be attributed to hole transitions to the Γ 7–8 and to the L 4–5 valence band extrema, respectively. The deduced Frank-Condon shift, d Fc = 0.23 eV, agrees with the measured difference of 40 meV between its apparent activation energy E a and its thermal activation energy E T.