n-GaN/AlxGa1-xN/n-GaN (n-I-n) heterostructure devices are investigated for potential applications as pressure sensors in extreme environments. Theoretical modeling of n-I-n sensors performed with various compositions (x = 0.1, 0.15, & 0.2) and thicknesses (10 nm and 20 nm) of AlxGa1-xN suggests that electrical current will decrease with increasing pressure and this effect becomes more significant with higher AlN compositions in the AlxGa1-xN layer and thicker AlxGa1-xN layer. The effects of hydrostatic pressure on the electrical properties of n-GaN/Al0.15Ga0.85N/n-GaN structures were also measured over the range of 0-6 kbar. The current was found to decrease linearly and reversibly with increasing pressure. The normalized change in current with pressure is consistent with our modeling studies. The linearity and reversibility in pressure response suggest that these newly investigated n-GaN/AlxGa1-xN/n-GaN devices are promising candidates for high-pressure sensor applications.