Project Iris: The Graphene Interface Simultaneous Stress Relief, 2DEG Enhancement, and Spin Hall Activation via a Single Graphene Monolayer at the Gd2O3/GaN Interface

We set out to make the interface smoother. The graphene did more than that. Project Iris places a single graphene monolayer at the Gd2O3/GaN interface of the Angelica architecture [1]. The motivation was mechanical: graphene’s Van der Waals compliance and exceptional elastic range suggested it could further reduce the residual thermal stress already lowered to 127.5 MPa by Angie’s Grading. It did. Stress falls to 112.5 MPa (−89.9% from the 1110 MPa Si/GaN baseline). But the graphene layer also enhances the two-dimensional electron gas (2DEG) den- sity by 6.8% via proximity effect, and — unexpectedly — amplifies the Rashba spin-orbit coupling (SOC) by 4.41×, activating Spin Hall conductivity of σSH = 1.852 (nor- malised units) without any external magnetic field. Three functions. One layer. None of the last two were designed. Keywords: graphene; GaN-on-Si; spin Hall effect; Rashba SOC; interface; 2DEG; Angelica series; Iris; neu- romorphic; spintronics.