In this work, an ultrathin plasma-enhanced atomic layer deposition (PEALD) alumina (Al2O3) was first introduced between top platinum (Pt) and underneath a-IZO. As consistently verified by experiment and simulation, such interlayer fundamentally eradicate the interface oxygen deficiency and MIGS, contributing to a much higher ΦB and noticeably JR, while the optimized ultrathin thickness readily allow the electron tunneling, resulting in minimal impact on the forward current.