IR reflection, attenuated total reflection, and Raman scattering of porous polar III-V semiconductors

• Published in: Physica status solidi. B. Basic research 2010-04, Vol.247 (4), p.955-961
• Main Authors: Dmitruk, Nicholas, Barlas, Tetyana, Dmitruk, Igor, Kutovyi, Sergiy, Berezovska, Natalia, Sabataityte, Julija, Simkiene, Irena
• Format: Article
• Language: English
• Subjects: attenuated total reflection; Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Iii-v and ii-vi semiconductors; Infrared and raman spectra and scattering; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; porous semiconductor; Raman scattering; Surface and interface electron states; surface phonon polariton
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.200945167

Optical properties of porous III–V compounds (GaAs, GaP, InP) in the far infrared (IR) reststrahlen region have been studied by IR reflection and attenuated total reflection (ATR). Comparison of obtained data with Raman scattering (RS) spectra have been performed. Porous layers on III–V compounds wafers were obtained by electrochemical etching. Morphology of porous layers was investigated by methods of atomic force microscopy (AFM) and scanning electron microscopy (SEM), including cross‐section measurements. The ATR measurements allow to study dispersion and damping of surface phonon polaritons (SPPs) in λ = 20–50 µm spectral region. The ATR measurements were carried out in Otto geometry under frequency‐scanning regime at several constant angles of incidence of light. The reflection spectra of porous samples demonstrate change of the reststrahlen band shape due to direct excitation of surface polaritons. It was enabled to excite mixed plasmon–phonon surface modes for semiconductors with free electron concentrations of 1017–1018 cm−3. Frequencies of bulk TO‐, LO‐phonons, surface phonons, and coupled plasmon–phonon modes in the case of high doped semiconductors have been obtained and compared for three spectroscopic methods – reflectance, ATR, and RS.