Well-width dependence of the in-plane effective mass and quantum lifetime of electrons in multiple quantum wells

Abstract

The electronic properties of modulation-doped GaAs/Ga 1−x Al x As multiple quantum wells (MWQ) with well width (L z ) in the range between 51 and 145 Å have been investigated by using the Shubnikov-de Haas (SdH) oscillations technique. The carrier density and the Fermi energy have been determined from the period of the SdH oscillations. The in-plane effective mass (m * ) and the quantum lifetime (τ q ) of 2D electrons have been obtained from the temperature and magnetic field dependences of the SdH amplitude. For narrow MQW samples (L z = 51, 75 and 78 Å), m * increases with decreasing L z ; for the samples with L z = 106 and 145 Å, m * is approximately equal to that of electrons in bulk GaAs. The values obtained for τ q show no clear well-width dependence and suggest that interface roughness is the dominating scattering mechanism in GaAs/Ga 1−x Al x As MQWs.

Effect of structural disorder on quantum oscillations in graphite

“…[28][29][30] Our results can also be compared to observations in highmobility two dimensional electron gases in semiconducting heterostructures. 31,32 In these systems, surface roughness is one of the key parameters limiting the electronic mobility. Results in Si MOSFETS and multilayered quantum wells show that the increase of roughness in these structures increases the scattering rate of the electron gas, prompting a reduction of the amplitude of the quantum oscillations.…”

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

“…Therefore, in order to exclude the effects of the background magnetoresistance (R b ) and to extract the SdH oscillations, we used the negative second derivative of the raw magnetoresistance data with respect to the magnetic field, i.e. (Ào 2 R xx /oB 2 ) [7,19,22,23]. The oscillations in the second derivative of magnetoresistance have well defined envelopes and are symmetrical about the horizontal line as shown in Fig.…”

“…Therefore, we employed the SdH oscillations technique in our investigations. The thermal damping of the amplitude of the SdH oscillations is, therefore, determined by the temperature, magnetic field, and effective mass via [7,19,[22][23][24][25][26]:…”

On the Role of Magnetic Field Fluctuations in Diffusive Shock Acceleration

“…This is, in turn, fixed by confining sources. It was indicated [2][3][4][5][6][7][8][9][10][11] that roughness-related scattering dominates transport in many heterostructures, especially thin square QWs. This is determined by the wave function near the interface.…”