Optical absorption and photoluminescence in the ternary chalcopyrite semiconductor AgInSe_2

摘要

Optical-absorption and photoluminescence (PL) spectra have been measured on the ternary chalcopyrite semiconductor AgInSe_2 at T=13-300 K. The direct-band-gap energy E_g of AgInSe_2 determined from the optical absorption measurements shows unusual temperature dependence at low temperatures. The resultant temperature coefficient partial deriv E_g/partial deriv T is found to be positive at T < 125 K and negative above 125 K. The PL spectra show asymmetric emission bands peaking at ～1.18 and ～1.20 eV at T=13K, which are attributed to donor-acceptor pair recombinations between exponentially tailed donor states and acceptor levels. An energy-band scheme has been proposed for the explanation of the peculiar PL emission spectra observed in AgInSe_2.