Mobility enhancement in recessed-gate AlGaN/GaN MOS-HFETs using an AlON gate insulator

Abstract

We demonstrated the advantage of aluminum oxynitride (AlON) gate insulator in enhancing the performance of recessed-gate AlGaN/GaN-based metal-oxide-semiconductor heterojunction field-effect transistors (MOS-HFETs) fabricated with reactive ion etching. The AlON deposition on the recessed-gate structures was found to mitigate the damage of recess etching on the GaN and AlGaN surfaces, enabling a simple gate recess process in the device fabrication. Consequently, a high field-effect mobility of 259 cm 2 V −1 s −1 , together with normally off operation, was achieved for the recessed-gate AlGaN/GaN MOS-HFETs with the AlON gate insulator. Temperature dependence of the transconductance of the fabricated devices revealed that carrier transport in the channel was mostly dominated by phonon scattering, indicating excellent interface quality between the AlON insulator and the recess-etched AlGaN surfaces.

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

“…The use of SiO 2 resulted into a poor interface quality displaying fast (interface) and slow (border) traps [136]. Dielectrics such as AlN [137], SiN [138], and their combination [139] have been also investigated as beneficial solutions to passivate surface N-vacancy, especially after recess etching damage in the gate region [140]. However, despite the good quality of the achieved interface and improved electron mobility, it was very difficult to obtain positive threshold voltages V th well beyond the zero [137].…”

“…Dielectrics such as AlN [137], SiN [138], and their combination [139] have been also investigated as beneficial solutions to passivate surface N-vacancy, especially after recess etching damage in the gate region [140]. However, despite the good quality of the achieved interface and improved electron mobility, it was very difficult to obtain positive threshold voltages V th well beyond the zero [137]. For these reasons, an increasing number of studies are focused on high-permittivity binary oxide layers for normally-off behaviour of AlGaN/GaN MISHEMTs.…”

Recent Advances in GaN‐Based Power HEMT Devices

“…Therefore, gate dielectric is significant for the recessed‐gate structure that can decrease off‐state gate leakage and driver losses. [ 44–46 ] Figure 1c,d shows two recessed‐gate normally‐off HEMT schematics. One is the partially recessed‐gate MIS‐HEMT structure with a residual thin AlGaN barrier under the gate dielectric.…”

Partially Crystallized Ultrathin Interfaces between GaN and SiNx Grown by Low-Pressure Chemical Vapor Deposition and Interface Editing

“…The growth and development of high-quality dielectrics is of exceptional importance for their incorporation into next-generation GaN high-electron-mobility transistors (HEMTs) because of their great potential in the radio frequency and power switching applications for both lateral and vertical devices. , The high-quality interface and the high tolerance to the electric stress are the main criteria and underlying challenges to both the material selection and growth. Various materials have been adopted on the (Al)­GaN surface as the passivation and gate dielectric layer to improve the device performance and reliability, such as SiO 2 , SiN x , , AlN, Al 2 O 3 , AlON, , HfO 2 , ZrO 2 , MgGaO, and AlSiO . Among them, SiN x dielectrics grown by low-pressure chemical vapor deposition (LPCVD) demonstrated excellent time-dependent dielectric breakdown (TDDB) properties in GaN MIS-HEMT .…”