A GAAS PRESSURE SENSOR-BASED ON RESONANT-TUNNELING DIODES

A GaAs/AlAs resonant tunnelling diode (RTD) is incorporated in a 1 mum thick membrane and used as a pressure sensor. The fabrication technol ogy of the membrane is based upon the selective etch of GaAs with AlAs as an etch stop layer. An external pressure introduces stress in the layers of the RTD and modifies the position of the conduction band, th e value of the effective mass and the Fermi level. These variations wi ll change the peak current and voltage of the RTD. Measurements at roo m temperature show that the effect of an applied pressure on a symmetr ic RTD is asymmetric. This asymmetric is explained theoretically by th e difference in the sign of the stress between the top and bottom laye rs of the RTD.