Dependence of offset voltage in AlGaN/GaN van der Pauw devices under mechanical strain

Abstract

This work reports the strain dependence of the offset voltage in an AlGaN/GaN van der Pauw device under mechanical strain. The AlGaN/GaN heterostructure was grown on a sapphire (0 0 0 1) wafer by using a metal organic chemical vapor deposition (MOCVD) process. Taking advantage of the four-terminal configuration, the fabricated van der Pauw device exhibited an excellent repeatability and linearity with a significant change of the offset voltage under application of tensile and compressive strains. In particular, the sensitivity of the device to the applied strain was found to be as large as 3 (µV/V)/ppm, indicating the feasibility of using this effect for mechanical sensing applications. The sensing mechanism of the device is explained via the alteration of the sheet carrier concentration at the AlGaN/GaN interface and the asymmetric current flux in the 2DEG van der Pauw device.