Photoluminescence Analysis of Deep Acceptor in CdTe Films on GaAs(100) Substrates

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In this study, we used photoluminescence (PL) measurement for analysis of deep acceptor states in unintentionally doped CdTe films on GaAs substrates. We analyzed PL and time-resolved spectra (TRS) in the vicinity of the 1.42 eV band. By analyzing the peak shift of the 1.42 eV band as a function of time after pulsed excitation, the bound-to-bound reaction constant for the unintentionally doped CdTe film on a GaAs substrate is estimated to be $W_{0}=4.0\times 10^{7}$ s-1. The impurity concentration in an unintentionally doped CdTe film is estimated to be $N=2.1\times 10^{16}$ cm-3. By analyzing the TRS of the 1.42 eV band as a function of time after pulsed excitation, the acceptor binding energy is estimated to be 105 meV. The acceptor binding energy is reasonably comparable to that in the case of a VII-donor-doped CdTe. The acceptor bound exciton, which can probably be attributed to a recombination of excitons bound to a complex acceptor consisting of a Cd vacancy and two Cl donors, is observed. From these features, it appears that the origin of the deep acceptor in unintentionally doped CdTe films on GaAs substrates is a complex acceptor consisting of a Cd vacancy and a Cl donor.
2010-08-25