AIGaAs/GaAs heterojunction hall device

Since the two-dimensinoal electron gas in the modulation-doped A1GaAs/GaAs heterojunction is as thin as 10 nm and the electron mobility is over 7000 cm2/Vs, this structure is suitable for highly sensitive Hall devices. As the room temperature device the following conditions must be satisfied: the carriers should be supplied sufficiently to the two-dimensional gas, but no excess carriers should exist in the highly doped A1GaAs layer. Thus the number of the two-dimensional electron gas should have little dependence on the temperature. The fabrication conditions of the heterojunction and the magnetic property of the devices are discussed. The product sensitivity and the figure of merit of the heterojunction Hall device were 1000 V/AT and 27 (V/A)1/2/T, respectively. These values are comparable to those of InSb Hall devices. The temperature dependence of our device was three times less than that of the InSb Hall device.