Donor-acceptor pair spectra in Si: In LPE-layers

We have grown In-doped silicon layers by liquid phase epitaxy. Samples grown with a small cooling rate display a large number of sharp lines in the low temperature photoluminescence spectra which can be interpreted as donor-acceptor pair transitions between the donor P and the acceptor In. At lower energies a broad band originating from distant pairs is observed. Samples grown with higher cooling rates exhibit only bound-exciton and intrinsic luminescence.