This article investigates low-high-low doped Ga2O3 Schottky barrier IMPATT diodes based on [100], [010], and [001] crystal orientations to promote oscillation power at the low-frequency band of terahertz regime. Simulation results demonstrate a conversion power of 4.88 MW/cm2 along [100] at its optimum frequency of 100 GHz, increasing by 0.73 times and 2.2 times compared to the [100] at 150 GHz and the [001] at 100 GHz, and exhibit the highest conversion efficiency of 6.83 % along [010] as indicated by the DC-RF conversion ability promoting 37 % and 30 % than that of [100] and [001] orientations, respectively. When considering a parasitic resistance of 1 × 10−5 Ω cm2, the optimal frequencies of along three orientations decrease to 90 GHz, 127 GHz, and 91 GHz, correspondingly, yielding the peak output power and total efficiency decrease by 0.3–0.4 times compared to those of the conversion characteristics.