Besides the commercial success in power electronics, GaN-based devices are also considered as a promising candidate in sensors or high-frequency applications. In such applications, ultra-low turn-on voltage (V
T) is highly demanded to realize low power consumption and high sensitivity. In this paper, we approach ultra-low V
T in a novel Γ-shaped anode AlGaN/GaN Schottky barrier diode (SBD) using an ultra-thin barrier (UTB) and fluorine ions implantation (FI). Benefiting from the low-work-function anode and UTB, the proposed device exhibits ultra-low V
T that is lower than 0.1 V. Simultaneously, the trenched anode plate and FI region provide a good reverse blocking capability. According to the numerical analysis, when the fluorine ions implantation length (L
FI) is 3 μm and the fluorine ions concentration (N
FI) is
1
×
10
18
cm−3, a favorable Baliga figure-of-merits (BFOM) of 33.0 KW mm−1 can be achieved. Compared to the conventional SBD and the SBD with pure Γ-shaped anode, the proposed device experiences at least 90% enhancement of BFOM, rendering the proposed ΓF-SBD performs potential in high-power and high-frequency applications such as microwave sensing and wireless power transmission.