Photoluminescence in high-quality a-Ge:H

We present quadrature frequency resolved spectroscopy (QFRS) measurements of photoluminescence (PL) in photoconductive and luminescent films of a-Ge:H with a defect density1 10 16 cm ˇ3 obtained from electron cyclotron resonance (ECR) plasma chemical vapor deposition (PCVD), together with a study of PL and PL excitation (PLE) spectra. A double-peak lifetime distribution is observed with a short lifetime at1 ls and a long one at0.1 ms as observed in a-Si:H. The dependence of the two lifetimes and their corresponding relative quantum eAciencies on the e‐h pair generation rate and temperature is also investigated. The occurrence of double peaks is attributed to the radiative recombination from singlet and triplet exciton states, and the exchange energy between singlet and triplet states is estimated to be3.3 meV in a-Ge:H. ” 2000 Published by Elsevier Science B.V. All rights reserved.