Electrical and Structural Analysis of β‐Ga2O3/GaN Wafer‐Bonded Heterojunctions with a ZnO Interlayer

Wafer bonding of β‐Ga2O3 and N‐polar GaN single crystal substrates is demonstrated by adding ZnO as a “glue” interlayer. The wafers are fully bonded such that Newton rings are not observed. Temperature‐dependent current‐voltage (I–V) measurements are conducted on the as‐bonded Ga2O3/ZnO/N‐polar GaN test structure and after annealing at 600 °C and 1100 °C. The impact of post‐annealing temperature on the electrical and structural characteristics of the bonded samples is investigated. A consistently ohmic‐like characteristic is obtained by annealing the bonded wafers at 1100 °C in N2, which is in part due to crystallization of ZnO and diffusion of Ga into ZnO which makes it n‐type doped. The wafer bonding of β‐Ga2O3 and GaN achieved in this work is promising to combine the material merits of both GaN and Ga2O3 targeting breakthrough high‐frequency and high‐power device performances. ZnO is used as a glue layer to achieve high yield and uniformity in wafer bonding of β‐Ga2O3 and GaN. Post‐bonding annealing eliminates the barrier to electron flow from GaN to Ga2O3 and vice versa. The electrical and structural analysis of β‐Ga2O3/GaN wafer‐bonded heterojunctions with a ZnO interlayer shows promise for the development of novel electronic and optoelectronic devices.