Study of the photoluminescence spectrum in high purity CdTe

In this work, a study of the photoluminescence produced by a high purity sample of n-type CdTe of f{hook}ND - NAf{hook} < 1014 impurities per cm3 was done at several temperatures, varying from 10 to 35 K. Several sharp lines were observed in the spectral region between 1.5 to 1.6 eV, plus the well-known 1.4 eV band with several well-defined structures on it. The observed temperature behaviour of the line positions, linewidths and relative intensities allowed us to establish the presence of a new transition, located at 10 K 21.3 meV below in energy from the free exciton (FE) line, as well as its first phonon replica. Its nature seems to be transitions originating from the conduction band to an acceptor level, 32 meV above the valence band. These two lines appear at the same position where previous works had reported the first and second phonon replicas of the FE. A scheme of impurity level is proposed to explain the observed transitions in terms of previously established levels and this new acceptor level. © 1983.

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