Anisotropic effective masses of electrons in AlAs

Abstract

The determination of longitudinal and transverse effective masses of electrons at the point X in the x-space in AlAs is an actual problem.Recently, we have reported on Faraday rotation study in n-type AlAs (1). The present note reports on further investigations of Faraday rotation due to free carriers in two AlAs samples, in order to determine the Faraday effective mass m* F'We have measured the room temperature rotation in the spectral range 1 pm I f a S 1 0 p m with a magnetic field B = 1.63 T. The material properties and the experimental results a r e very like those described in the earlier paper (1).For the interpretation we have used the rotation angles 8 in the spectral range 2 -A and Hall coefficients measured at room temperature on the with ' free car. same samples. The theoretical connection between the longitudinal mass m the transverse II ' mass m coefficient R, and the electron concentration N is given by the following equations the Faraday effect mass m; , the Verdet coefficient 8/Bd, the Hall I' (2, 3): 2 (2) e3 h2 -e2 n2 2 (K + 2) 2 . m2 (2K t 1) 2 3 = N e -1 Bd 8% c n e m * 2 -8'It2c3n co O F ( e is the permittivity of the space and c is the vacuum velocitg of light). In 2 equation (1) the scattering time factor was set <Z )/ (2," = 1, because any data on the scattering mechanisms in AlAs are absent. For the refractive index n we have taken the value n = 2.9 (4). 0 12 physica (b)

Γ to X electron transfer times in type-II GaAs/AlAs superlattices due to emission of confined and interface phonons

“…The measured AlAs transversal and longitudinal X-valley effective masses are 0.44m 0 and 2.62m 0 , respectively, where m 0 is the free electron mass. These values are much heavier than the commonly used values of 0.19m 0 and 1.1m 0 obtained from Faraday rotation (FR) studies [13,14]. We recently calculated donor binding energies using the CR effective masses which are in better agreement with experimental measurements [15] than those calculated with the FR masses.…”

Energy-Band Structure: Electron and Hole Effective Masses

“…16 Rheinlander et al 34 has obtained the masses n^x^.^m,, and m tx =l.lm 0 from an investigation of Faraday rotation in n-AlAs. These masses correspond to m e x =0.71m 0 and m c x =0.26m 0 .…”

Generation of Raman radiation in a long stimulated-Raman-scattering medium

“…To describe the electron states of a GaAs/AlAs type I1 quantum well completely we must take into account the threefold degeneracy of the AlAs X minimum. For the X electron states with k perpendicular to [OOl], Xxy, the effective mass which determines the confinement energy is the transverse mass (0.19m0) [3] whereas for those states with k parallel to [OOl], X,, we must consider the longitudinal effective mass (l.lmo) [3]. Clearly, from considerations of the effective masses alone we might anticipate that the X, confined states would always lie below the X,.. states [4,5].…”