High-performance enhancement-mode (E-mode) AlN/GaN metal-oxide-semiconductor heterojunction field-effect transistors (MOSHFETs) on Si substrates have been demonstrated. Record high peak transconductance Gm of 509 mS/mm and maximum drain current Id of 860 mA/mm were achieved for E-mode MOSHFETs with a source/drain spacing value Lsd of 0.7 m. Low gate leakage current (<;10-3 mA/mm) and improved ohmic contact resistance (0.153 Ω·mm) were enabled by a combination of Al2O3 gate dielectric and regrown source/drain contacts. Al2O3 also significantly increases the 2DEG density under the channel, which is beneficial for device performance by reducing the access resistance. The on-resistance is as low as 1.63 mm. The average regrowth interface resistance across the sample was estimated to be 0.056 Ω·mm. The E-mode MOSHFETs exhibit a high Ion/Ioff ratio up to 106.