Piezoresistive effect in wurtzite <i>n</i>-type GaN

We report on the measurements of the piezoresistive effect in the n-type wurtzite GaN films. The 3–5 μm thick GaN layers were deposited slightly off axis over basal plane sapphire substrates. The static and dynamic gauge factor (GF) of these structures was measured at room temperature for both longitudinal and transverse configurations. The dynamic effect is related to a strong piezoeffect in GaN. The maximum dynamic GF observed was ∼130 (approximately four times larger than for SiC).