Band offset of Al_1−xSi_xO_ymixed oxide on GaN evaluated by hard X-ray photoelectron spectroscopy

Abstract

An Al 1%x Si x O y mixed oxide has been deposited on GaN by plasma-enhanced atomic layer deposition. The band diagrams between the mixed oxide and GaN for various Si atom fraction x values are determined by hard X-ray photoelectron spectroscopy for the first time. The band gap of the mixed oxide increases with increasing x. This dependence has a large bowing parameter of 1.5 eV. We have successfully obtained conduction band offset (ΔE C ) and valence band offset (ΔE V ) as a function of x: ΔE C (eV) = 1.6 + 0.4x + 1.2x 2 and ΔE V (eV) = 1.7 + 0.34x + 0.36x 2 . These relationships enable us to design GaN metal-oxide-semiconductor devices using the Al 1%x Si x O y mixed oxide.

The Influence of Ga–OH Bond at Initial GaN Surface on the Electrical Characteristics of SiO2/GaN Interface

“…Metal–oxide–semiconductor (MOS) structures with a deposited gate insulator have been intensively investigated for realizing such devices. As the insulating films of GaN power devices require large band offsets, the gate dielectric in most studies is SiO 2 or Al 2 O 3 , but AlON and AlSiO can reportedly reduce the number of defects and improve the fabrication process. The nitrogen incorporated in the alumina of AlON film reduces the electrical defects in the insulator and improves the stability against charge injection.…”

Theoretical prediction of a self-forming gallium oxide layer at an n-type GaN/SiO2interface

“…4,5) On the other hand, there have been several studies on various metal-oxide-semiconductor (MOS) gate structures, each designed to obtain high threshold voltages and suppress the gate leakage current. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] In the case of MOS field-effect transistors (FETs), the threshold voltage can be controlled by selecting the gate electrode material and the dopant density in the semiconductor layer, and the gate current can be effectively reduced by the choice of oxide. In terms of reliability, MOS gate structures have advantages for highpower-density devices.…”

“…Considering the need for a sufficiently high conduction band offset (CBO), the possible dielectric films for GaN are limited to a few materials with large bandgaps, such as SiO 2 and Al 2 O 3 . [10][11][12]19,20) Of the candidate materials, SiO 2 is very promising, not simply because it has a very large bandgap but because a great deal of knowledge about SiO 2 has been accumulated as a result of the work done on Si and SiC. Experimental measurements of the interface-trap density and the band offset of the GaN=SiO 2 interface have been reported.…”

Over 200 cm2 V−1 s−1 of electron inversion channel mobility for AlSiO/GaN MOSFET with nitrided interface

“…The reliability of the gate oxide is another important issue for MOSFETs. To obtain sufficient insulating properties, oxides having sufficient band offsets for GaN, such as alumina (Al 2 O 3 ), 11,[13][14][15] silicon dioxide (SiO 2 ), [6][7][8][9][10]12,16) and their composite (AlSiO), [17][18][19][20] have been investigated. We previously developed an AlSiO gate oxide that exhibits a long lifetime (20 years under 5 MV cm −1 at 150 °C) and demonstrates minimized positive bias temperature instability, where a post-deposition annealing (PDA) process was key.…”