AVS 57th International Symposium & Exhibition
    Spectroscopic Ellipsometry Focus Topic Thursday Sessions
       Session EL+AS+EM+MS+TF-ThP

Paper EL+AS+EM+MS+TF-ThP1
Temperature Dependence of the Dielectric Function of AlSb Measured by Spectroscopic Ellipsometry

Thursday, October 21, 2010, 6:00 pm, Room Southwest Exhibit Hall

Session: Spectroscopic Ellipsometry Focus Topic Poster Session
Presenter: J.J. Yoon, Kyung Hee University, Republic of Korea
Authors: J.J. Yoon, Kyung Hee University, Republic of Korea
Y.W. Jung, Kyung Hee University, Republic of Korea
J.S. Byun, Kyung Hee University, Republic of Korea
S.Y. Hwang, Kyung Hee University, Republic of Korea
Y.D. Kim, Kyung Hee University, Republic of Korea
S.H. Shin, Korea Institute of Science and Technology, Republic of Korea
S.Y. Kim, Korea Institute of Science and Technology, Republic of Korea
J.D. Song, Korea Institute of Science and Technology, Republic of Korea
Correspondent: Click to Email
AlSb is a promising material for applications in heterostructure devices such as long-wavelength detectors, quantum-well lasers, and laser diodes. However, to understand and properly design these devices, information about its electronic properties and its dielectric function ε = ε1 + iε2 is needed. While room-temperature ε data for AlSb exist, very little information is available about its behavior at elevated temperatures. Here, we report pseudodielectric function data <ε> from 300 to 800 K and from 0.7 to 5.0 eV, determined by spectroscopic ellipsometry. The samples were 1.5 μm thick layers grown on GaAs (001) substrates by molecular beam epitaxy (MBE). This thickness significantly exceeds the critical value for AlSb, so the layers are fully relaxed. The MBE station features an integrated spectroscopic ellipsometer and strain-free windows, thereby allowing e data to be obtained without exposing the samples to air. For AlSb this is critical, because the removal of its oxides is not feasible owing to its reactivity. As a result of these precautions and the method by which these <ε> data were obtained, we consider them to be the most accurate representation of ε to date. We also analyzed these data for critical-point (CP) parameters by fitting numerically calculated second energy derivatives of to standard analytic CP lineshape expressions. A parametric model was used, which describes dielectric functions by a combination of energy-bounded polynomials and poles, and encodes information in terms of amplitudes, critical-point energies, and broadening parameters. The reconstructed spectra are in excellent agreement with the data. We use these parameters to obtain information about the individual oscillators, including phonon effects, and interpolate them to obtain an analytic representation of the dielectric response of AlSb as a function of temperature. We expect these results to be an important database supporting engineering design, device technologies, and in-situ monitoring and control of device fabrication.