Piezoresistive and piezoelectric effects in GaN

Abstract

Abstract Gallium nitride is known to have both piezoelectric and piezoresistive properties (A. D. Bykhovski et al., Appl. Phys. Lett. 68 , 818 (1996) [1] and R. Gaska et al., Appl. Phys. Lett. 71 , 3817(1997) [2]). GaN's inertness to corrosive chemicals and robustness to high temperature makes it a potential candidate for harsh environment pressure sensor applications. We report piezoresistive and piezoelectric gauge factor measurements done on n‐GaN. Resistor structures were fabricated on 1×10 18 cm –3 n‐type doped 250 μm thick GaN and subject to three point bend tests. The gauge factor was measured to be 28 at room temperature. The sample was also heated to 125 °C and the gauge factor was measured to be 17. Metal‐Insulator‐Semiconductor capacitor structures were fabricated on 7×10 16 cm –3 n‐typed doped 2 μm thick GaN grown by MOCVD. Three point bend tests were done on the capacitors. The gauge factor was determined at both room temperature to be 167 and at 250 °C to be 104. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)