Micromachined membrane structures for pressure sensors based on AlGaN/GaN circular HEMT sensing device

Graphical abstractDisplay Omitted Highlights¿ We designed a pressure sensor based on circular high electron mobility transistor. ¿ The 1.9µm thick AlGaN/GaN membrane is fabricated by reactive ion etching of the Si. ¿ The membrane tensile residual stress is about 280-300MPa. ¿ The maximal membrane deflection about 2.75µm is for the applied pressure of 1MPa. A new design concept of pressure sensors based on circular high electron mobility transistor (C-HEMT) sensing devices integrated on circular, ring and/or sequential ring AlGaN/GaN membrane structures is introduced for the first time. The micromachining process technology of 1.9µm thick AlGaN/GaN membrane structures patterned on Silicon substrate is experimentally verified. The mechanical properties of the membranes are investigated by two different experimental methods and simulation. They reveal the membrane tensile residual stress of the value about 280-300MPa. A non-linear behavior of maximal deflection with the applied pressure is predicted by the ANSYS simulation. The maximal membrane deflection about 2.75µm is estimated for the applied pressure of 1MPa. The functionality of the integrated membrane-based C-HEMT sensing device is successfully verified to be applied for pressure sensing.