A1Sb/InAs quantum well (QW) structures and InAs films on GaAs (001) substrates were grown by molecular beam epitaxy (MBE). We investigated the dependence of electron mobility and two-dimensional electron gas (2DEG) concen- tration on the thickness of an InAs Channel. It is found that electron mobility as high as 19050 cm2 · V-1 · s-1 has been achieved for an InAs channel of 22.5 nm. The Hall devices with high sensitivity and good temperature stability were fabricated based on the A1Sb/InAs QW structures. Their sensitivity is markedly superior to Hall devices of InAs films.