GaAs–AlAs heterojunctions under hydrostatic pressure

We report magnetotransport measurements made at 4.2 K on GaAs–AlAs modulation-doped heterojunctions under hydrostatic pressure. The two-dimensional electron-gas concentration is observed to decrease linearly from 1.5 × 1011 cm−2 to 0 cm−2 when the pressure is increased from 1 bar to [Formula: see text] (1 bar = 100 kPa). The relative movement, induced by pressure, between the X band in AlAs (dEX/dP = −1.7 meV/kbar) and the Γ band in GaAs (dEΓ/dP = 10.7 meV/kbar) can account for about 65% of the decrease. Different possibilities are examined in order to interpret the remaining 35%.