Browsing by Subject "Phonon emission"

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    Energy relaxation rates in AlInN/AlN/GaN heterostructures
    (Springer, 2012-06-27) Tiras, E.; Ardali, S.; Arslan, E.; Özbay, Ekmel
    The two-dimensional (2D) electron energy relaxation in Al0.83In0.17N/AlN/GaN heterostructures has been investigated experimentally. Shubnikov-de Haas (SdH) effect measurements were employed in the investigations. The electron temperature (T (e)) of hot electrons was obtained from the lattice temperature (T (L)) and the applied electric field dependencies of the amplitude of SdH oscillations. The experimental results for the electron temperature dependence of power loss are also compared with current theoretical models for power loss in 2D semiconductors. The power loss from the electrons was found to be proportional to (T (e) (3) - T (L) (3) ) for electron temperatures in the range 1.8 K < T (e) < 14 K, indicating that the energy relaxation of electrons is due to acoustic phonon emission via unscreened piezoelectric interaction. The effective mass and quantum lifetime of the 2D electrons have been determined from the temperature and magnetic field dependencies of the amplitude of SdH oscillations, respectively. The values obtained for quantum lifetime suggest that remote ionized impurity scattering is the dominant scattering mechanism in Al0.83In0.17N/AlN/GaN heterostructures.
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    Temperature dependent energy relaxation time in AlGaN/AlN/GaN heterostructures
    (2012) Tiras, E.; Celik O.; Mutlu, S.; Ardali, S.; Lisesivdin, S.B.; Özbay, Ekmel
    The two-dimensional (2D) electron energy relaxation in Al 0.25Ga 0.75N/AlN/GaN heterostructures was investigated experimentally by using two experimental techniques; Shubnikov-de Haas (SdH) effect and classical Hall Effect. The electron temperature (T e) of hot electrons was obtained from the lattice temperature (T L) and the applied electric field dependencies of the amplitude of SdH oscillations and Hall mobility. The experimental results for the electron temperature dependence of power loss are also compared with the current theoretical models for power loss in 2D semiconductors. The power loss that was determined from the SdH measurements indicates that the energy relaxation of electrons is due to acoustic phonon emission via unscreened piezoelectric interaction. In addition, the power loss from the electrons obtained from Hall mobility for electron temperatures in the range T e > 100 K is associated with optical phonon emission. The temperature dependent energy relaxation time in Al 0.25Ga 0.75N/AlN/GaN heterostructures that was determined from the power loss data indicates that hot electrons relax spontaneously with MHz to THz emission with increasing temperatures. © 2012 Elsevier Ltd. All rights reserved.