Recess-Free E-Mode AlGaN/GaN MIS-HFET with Crystalline PEALD AlN Passivation Process

We utilized a plasma-enhanced atomic layer deposition (PEALD) process to deposit an AlN passivation layer on AlGaN/GaN surface to enhance the polarization effects, which enabled the fabrication of an enhancement-mode (E-mode) AlGaN/GaN metal-insulator-semiconductor heterojunction field-effect transistor (MIS-HFET) without the need for a gate recess process. The AlN film deposited by PEALD exhibited a crystalline structure, not an amorphous one. The enhanced polarization effect of introducing the PEALD AlN film on a thin AlGaN barrier was confirmed through electrical analysis. To fabricate the E-mode AlGaN/GaN MIS-HFET, the PEALD AlN film was deposited on a 4.5 nm AlGaN barrier layer and then a damage-free wet etching process was used to open the gate region. The MIS-gate structure was formed by depositing a 15 nm plasma-enhanced chemical vapor deposition (PECVD) silicon dioxide (SiO2) film. The fabricated thin-AlGaN/GaN MIS-HFET demonstrated successful E-mode operation, with a threshold voltage of 0.45 V, an on/off ratio of approximately 10(9), a specific on-resistance of 7.1 m?center dot cm(2), and an off-state breakdown voltage exceeding 1100 V.

Automated summary

We utilized a plasma-enhanced atomic layer deposition (PEALD) process to deposit a crystalline AlN passivation layer on the surface of AlGaN/GaN, enhancing the polarization effects and enabling the fabrication of an enhancement-mode (E-mode) AlGaN/GaN metal-insulator-semiconductor heterojunction field-effect transistor (MIS-HFET) without a gate recess process. Through electrical analysis, we confirmed the enhanced polarization effect of the PEALD AlN film on the thin AlGaN barrier. By depositing the PEALD AlN film on a 4.5 nm AlGaN barrier layer and using a damage-free wet etching process, we successfully fabricated an E-mode AlGaN/GaN MIS-HFET with high performance.