OPTICAL STUDIES ON INP-FE BY FOURIER-TRANSFORM EMISSION AND ABSORPTION-SPECTROSCOPY

We present highly resolved photoluminescence (PL) and absorption spectra of the internal d-d-shell transitions at Fe2+ in InP and the related phonon sidebands. By use of the Fourier-transform-infrared technique, the signal-to-noise ratio (SNR) is improved by about two orders of magnitude as compared to conventional dispersive techniques. Thus we are able to resolve new fine structure in the zero-phonon lines of Fe2+ in both absorption and PL. This fine structure is identified as shift induced by different iron isotopes. A better SNR also reveals several new features in PL spectra of the phonon sidebands. In absorption measurements Fe2+ related spectra in the energetic range of 2800 to 3400 cm-1 (almost-equal-to 0.35-0.4 eV) are recorded, which can be partly attributed to anti-Stokes lines of phonon coupling in emission. Additional peaks at 3103 and 3117 cm-1 are interpreted as transitions from the 5E ground state to an excited state of the 5T2 manifold of Fe2+.