Piezoelectric Properties of GaN-on-Si Heterostructures and Their Implications on Lifetime During Switching Operation

Due to the intrinsic piezoelectric nature of gallium nitride (GaN), devices manufactured with such technology are in principle prone to experience electromechanically induced resonance phenomena during cyclic switching operation. We will outline an approach to model the mechanical resonance in a GaN-on-Si test heterostructure and evaluate the implication of the stresses in the resonance case. A reliability assessment for the GaN and the die attach layer will be derived. We demonstrate the method for a test structure assembled in a TO-220 package, and discuss further cases where mechanical damping effects are minimized. The results show that the analysed GaN chip is safe in terms of long-term reliability with respect to mechanical resonance phenomena.