Effect of external strain on the conductivity of AlGaN/GaN high electron mobility transistors

The changes in conductance of the channel of AlGaN/GaN high electron mobility transistor structures during application of both tensile and compressive strain were measured. For fixed Al mole fraction, the changes in conductance were roughly linear over the range up to 2.7x 10 8 N.cm -2 , with coefficients for planar devices of -6.0 +/- 2.5 x 10 -10 S.N -1 .m -2 for tensile strain and +9.5+/-3.5 x10 -10 S.N -1 .m -2 for compressive strain .For mesa-isolated structures, the coefficients were smaller due to the reduced effect of the AlGaN strain, with values of 5.5 +/- 1.1 x10 -13 S.N -1 .m -2 for tensile strain and 4.8 x10 -13 S.N -1 .m -2 for compressive strain. The large changes in conductance demonstrate that simple AlGaN/GaN heterostructures are promising for pressure and strain sensor applications.

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