Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

Abstract

Abstract:The longitudinal optical (LO) phonon energy in AlGaN/GaN heterostructures is determined from temperature-dependent Hall effect measurements and also from Infrared (IR) spectroscopy and Raman spectroscopy. The Hall effect measurements on AlGaN/GaN heterostructures grown by MOCVD have been carried out as a function of temperature in the range 1.8-275 K at a fixed magnetic field. The IR and Raman spectroscopy measurements have been carried out at room temperature. The experimental data for the temperature dependence of the Hall mobility were compared with the calculated electron mobility. In the calculations of electron mobility, polar optical phonon scattering, ionized impurity scattering, background impurity scattering, interface roughness, piezoelectric scattering, acoustic phonon scattering and dislocation scattering were taken into account at all temperatures. The result is that at low temperatures interface roughness scattering is the dominant scattering mechanism and at high temperatures polar optical phonon scattering is dominant. PACS

Temperature dependent energy relaxation time in AlGaN/AlN/GaN heterostructures

“…6(b). Although the calculated power loss does not offer a satisfactory fit to the experimental data in the electron temperature range between 20 and 150 K, it fits reasonably well to the experimental data for T e > 150 K. From the temperature dependence of the Hall mobility compared with the calculated various electron mobility was shown that the mobility of electrons in Al 0.25 Ga 0.75 N/AlN/GaN heterostructures is determined by mixed interface roughness scattering and polar optical phonon scattering in the temperature range between 20 and 150 K [21]. Therefore, it is clear that the addition of the other scattering time together with the optical phonon scattering time is necessary in the definition of the electron-phonon scattering time (Eq.…”

“…1). This behavior reflects the 2D character of the electrons in the channel [19][20][21]. It is also evident that the oscillatory effect is superimposed on a monotonically increasing component, which occurs as a result of positive magnetoresistance in the barriers [7,19].…”

“…(7), has been calculated using the values (Table 1) determined experimentally [21,32] for the effective mass, longitudinal optical phonon energy, carrier density and Fermi energy of 2D electrons in the Al 0.25 Ga 0.75 N/AlN/GaN heterostructure sample; other parameters are taken from the literature [15,[33][34][35].…”

Fully numerical analysis of III-nitride based quantum dot lasers considering the quantum dots size distribution

“…One of the most important parameter in the rate equations is the inter-level electron relaxation lifetime. In this paper, we calculated the inter-level electron relaxation lifetime due to the different scattering mechanisms [5,19,20]. We found it in order of 1 ps, for example, 0.21 ps at T = 300 K, and 0.46 ps at T = 250 K.…”

Magneto-ballistic transport in GaN nanowires

“…1 This regime occurs when electrons travel a distance shorter than their mean free path l m (average distance between consecutive scattering events), which can be as small as tens of nanometers depending on the material. Therefore, ballistic transport is a nanoscale phenomenon, requiring nanoscale structures.…”