Effects of postmetallization annealing on interface properties of Al₂O₃/GaN structures

Abstract

In this study, we investigated the effects of postmetallization annealing (PMA) on the interface properties of GaN metal-oxide-semiconductor (MOS) structures using Al 2 O 3 prepared by atomic layer deposition. Excellent capacitance-voltage (C-V ) characteristics without frequency dispersion were observed in the MOS sample after PMA in N 2 ambient at 300-400 °C. The PMA sample showed state densities of only at most 4 ' 10 10 cm %1 eV %1 . A geometric phase analysis of transmission electron microscopy images after PMA revealed a uniform distribution of the lattice constant near the Al 2 O 3 /GaN interface, leading to the improved bond termination and bonding order configuration along the interface.

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.…”

Evaluate Fixed Charge and Oxide‐Trapped Charge on SiO2/GaN Metal‐Oxide‐Semiconductor Structure Before and After Postannealing

“…Comparing D it before and after PMA, it can be seen that D it was reduced at around E c – E = 0.6 eV after PMA even though D it was almost constant at around 0.2 eV. Although D it was reduced by PMA, it has been reported that the reduction is less than 1/100 in the case of the Al 2 O 3 /GaN MOS structure . This indicates that the effect of PMA on SiO 2 /GaN is small compared with that of Al 2 O 3 /GaN.…”

“…PMA is known to be effective at reducing dielectric/Si interface charges at relatively low temperatures (about 400 °C) . For GaN MOS devices, previous reports have been made not only on the effects of the reducing interface state density but also for suppressing the flat‐band voltage shift . Another important issue for the practical use of GaN MOSFETs is reliability issues such as threshold voltage destabilization due to charge trapping in the gate dielectric or dielectric/GaN interface .…”

Low-Damage Etching for AlGaN/GaN HEMTs Using Photo-Electrochemical Reactions

“…The PMA successfully made the Vth shift in the forward bias regime and enhanced the maximum transconductance value (gm) from 60 to 66 mS/mm. A possible mechanism for the positive Vth shift and gm enhancement after PMA may originate from the decrease in oxygen-related defects in the Al2O3/AlGaN system and subsequent shrinkage of the ALD-Al2O3 film caused by the relaxation of dangling bonds [19,20].…”