Enhancement-Mode AlN/GaN MOSHFETs on Si Substrate With Regrown Source/Drain by MOCVD

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 G_m of 509 mS/mm and maximum drain current I_d of 860 mA/mm were achieved for E-mode MOSHFETs with a source/drain spacing value L_sd 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 I_on/I_off ratio up to 10⁶.