Determination of the In-Plane Effective Mass and Quantum Lifetime of 2D Electrons in Modulation-Doped In0.53Ga0.47As/In0.52Al0.48As Heterojunctions from the Quantum Oscillations in Hall Resistance

Abstract

Hall effect measurements as a function of magnetic field up to 2.3 T, performed in the temperature range between 3.3 and 12 K, have been used to investigate the electronic transport properties of modulation-doped In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As heterojunctions with single-or double-subband occupancy. The carrier density (N i ) in each subband, the Fermi energy (E F --E i ) with respect to subband energy and subband separation (E 2 --E 1 ) have been determined from the periods of the quantum oscillations in Hall resistance. The in-plane effective mass (m * ) and the quantum lifetime (t q ) of 2D electrons in each subband have been obtained from the temperature and magnetic field dependences of the amplitude of the Hall oscillations, respectively. The results found for N i , E F --E i , E 2 --E 1 , m * and t q are in good agreement with those determined from Shubnikov-de Haas effect in magnetoresistance. It is shown that the experimental technique employed in the current study is equally successful in determining the effective scattering mechanisms in highly-degenerate 2D structures at low temperatures. The results obtained for transport-to-quantum lifetime ratio suggest that the scattering of electrons in the first subband of modulation-doped In 0.53 Ga 0.47 As/ In 0.52 Al 0.48 As heterojunctions is, on average, forward displaced in momentum space, while the scattering of electrons in the second subband contains some contribution from large-angle scattering.

Hot electron energy relaxation via acoustic-phonon emission in GaAs/Ga1 xAlxAs multiple quantum wells: well-width dependence

“…It is also clear from figure 1 that the background magnetoresistance, which makes it difficult to determine the oscillation amplitude, differs from one sample to another. A widely used method to exclude the effects of the background magnetoresistance and to extract the SdH oscillations is to calculate the negative second derivative −∂ 2 R xx /∂B 2 of the experimental magnetoresistance data with respect to the magnetic field [3,22,[33][34][35][36]. The result of this procedure is also illustrated in figure 1.…”

“…The SdH oscillations in magnetoresistance provide an accurate and sensitive technique that has been used successfully in investigations of electron energy relaxation in the acoustic-phonon regime (see for example [22] and references therein). In heavily modulation-doped 2D structures, where a highly-degenerate electron gas exists, the variations of the amplitude of the SdH oscillations with applied electric field and lattice temperature can be used in the determination of the power loss-electron temperature characteristics.…”

“…Experimental research on the energy-loss rates of 2D electrons in the acoustic-phonon scattering regime has been reported by a large number of groups [3,[9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Most of the research reported previously in the literature, however, has been carried out on high electron mobility transistor (HEMT) structures, where the interpretation of the experimental results is often complicated by a number of factors; for example, existing theories are based on the ideal quantum-well approximation with single-subband occupancy and, therefore, predict a power loss with a strong dependence on the confinement length.…”

The effect of barrier layers on 2D electron effective mass in Al0.3Ga0.7N/AlN/GaN heterostructures

“…The SdH oscillations are obtained by eliminating the monotonic resistance from the data of the magnetoresistance. The monotonic term of resistance is known to be dependent on the quadratic magnetic field [17,27,28]. There are two methods to remove the effect of monotonic resistance.…”

“…When the F_S sample and F_D_S (0.22 ± 0.005)m 0 sample are compared, Si doping in the AlGaN barrier surpasses the spacer layer's effect and causes an increase in the effective mass. This behavior is because the Si-doped AlGaN barrier layer causes a change in band energy [27], and this change leads to penetration of electron wave function to the barrier layer. Therefore, effective mass is affected.…”