Residual stress characterization of GaN microstructures using bent-beam strain sensors

One to the thermal mismatch between GaN and Si, GaN grown on Si at elevated temperatures (??1100 ?? C) usually exhibits large internal residual stress. Therefore, the characterization of residual stress in GaN on Si substrate is of particular importance. In this work, a type of reliable bent-beam strain sensor was used to estimate residual stress in suspended GaN microstructures. The device was modeled by finite element method (FEM) and was fabricated by a dry-etch-only deep-releasing technique featuring a combination of anisotropic and isotropic Si etching. Results were analyzed and an averaged residual stress value of ?? 575 ?? 5 MPa was estimated for the GaN sample used in this work. ?2010 IEEE.EI