ISSN:
1432-0630
Schlagwort(e):
72.20.Fr
;
72.20.Ht
;
72.20.My
;
73.40.Lq
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract The transport properties of warm and hot electrons in selectively dopedn-Al x Ga1−x As/GaAs heterostructures created by electric fields up to 500 V/cm were studied by Hall effect, conductivity, and Shubnikov-de Haas measurements at lattice temperatures from 4.2 to 300 K. Hall measurements revealed a substantial decrease of electron mobility and also of sheet electron concentration at 77 K with enhanced electric field. The accelerated 2D electrons are partly scattered into the low-mobility first excited (E 1) subband, and they are partly trapped in immobile states located in the AlxGa1−xAs near the interface. Consequently, two differentv(E) characteristics were obtained at 77 K. The 2D electrons populating only the lowest (E 0) subband exhibit a velocity of v∼-2×107 cm/s at 500 V/cm, while the averaged velocity due to all electrons reaches a value of v∼-1.5×107cm/s at 500 V/cm. The analysis of the Shubnikov-de Haas oscillations and Fast Fourier transformation of the data manifested that the 2D electrons are very rapidly accelerated at 4.2 K and achieve electron temperatures much higher than the lattice temperature at electric fields as low as 1 V/cm. The major cooling process for these electrons is scattering into the low-mobilityE 1 subband.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00618754
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