Ohmic contact to n-AlGaN through bonding state transition at TiAl interface

Abstract

We report the optimized ohmic contact to high Al content n-AlGaN through modification of the interfacial bonding state of TiAl alloy. First-principles calculations demonstrate that the change of interfacial bonding state (N rich to Al rich) at the TiAl/n-AlGaN interface is crucial for the formation of low barrier contact. The significant electron-transfer and strong orbital hybridization between the Ti atoms and the nearest Al atoms plays a key role in lowering the contact barrier. After treatment of the TiAl/n-AlGaN sample via rapid thermal annealing, perfectly linear I-V characteristic is achieved and the elemental profile by Auger electron spectroscopy confirms the N-rich-to-Al-rich local state transition in the interfacial layers. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4727848

Role of Al and Ti for ohmic contact formation in AlGaN/GaN heterostructures

“…Noticeable deficiency in N, reported in Ref. 19, was not observed in the present work, suggesting that N-vacancy and/or Ti-N complex formation was not essential for the increase in n s and l.…”

“…7,8,14,15 However, there are several exceptions, for example, a low resistive ohmic contact is obtained by V (vanadium) instead of Ti 16 and a spike is not always observed in the ohmic contact. 10,17,18 Recently, Zhang et al 19 proposed a model for ohmic contact formation that AlGaN surface was changed from N-rich to Al-rich and reduced the barrier height by formation of Al-Ti bonds, resulting in low contact resistance. In any case, the mechanism of ohmic contact formation is still under debate.…”

Schottky Barrier Formation and Strain at the (011)GdN/GaNInterface from First Principles

“…To visualize the real-space band structure across the interface, we evaluate the real-space density of states ρðz; EÞ projected onto the normal direction z of the interface [54][55][56][57][58][59][60][61]. This projection is calculated for majority and minority spins σ ¼ AE as…”

Enhanced Emission of Deep Ultraviolet Light-Emitting Diodes through Using Work Function Tunable Cu Nanowires as the Top Transparent Electrode

“…The formation of alloy interface plays a significant role in increasing the injection current density greatly for most electrodes, which could finally lead to ohmic contact . For traditional planar metal electrodes used in the AlGaN conducting layer, e.g., n-type AlGaN, the annealing temperature can come up to 800–900 °C . This means that an annealing temperature higher than 300 °C should be necessary for making the effective alloy interface.…”

“…44 For traditional planar metal electrodes used in the AlGaN conducting layer, e.g., n-type AlGaN, the annealing temperature can come up to 800−900 °C. 45 This means that an annealing temperature higher than 300 °C should be necessary for making the effective alloy interface. For bulk Cu, the melting point is about 1080 °C in vacuum, whereas for the nanostructured Cu materials the melting point could become much lower (around 400−500 °C).…”