Formation of low resistance Pt ohmic contacts to <i>p</i>-type GaN using two-step surface treatment

Jang, Ja-Soon; Park, Seong Ju; Seong, Tae Yeon

doi:10.1116/1.591045

Cited by 113 publications

(76 citation statements)

References 13 publications

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“…This is further complicated by the fact that oxide reaily forms at the GaN surface [2]. Currently, lowering of contact resistivity is commonly achieved by reducing oxide and contamination at the surface with various cleaning recipes, the most effective of which reported is the use of boiling aqua regia [3] or (NH 4 ) 2 S x [4].…”

Section: Introductionmentioning

confidence: 98%

Low resistivity contacts to p‐type GaN by plasma treatment

Choi

Jeon

Dawson

2003

phys. stat. sol. (c)

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A N-2-based plasma has been applied to a p-type GaN surface in order to improve contact resistivity. It has been found that the dc bias voltage of the plasma, which dictates the energies of incident ions, plays an important role in the effectiveness of the treatment. A reduction of contact resistivity has been achieved with a plasma of -75 V de bias voltage. Excessive ion energies result in a deterioration of the contacts, as a result of plasma damage. The result is supported by XPS data, where a decrease of contact resistivity is linked to a shift of the binding energy of the Ga 3d core level towards lower energies. Such a shift indicates a reduction of the surface band bending coincident with an decrease of the surface barrier height, giving rise to a decrease contact resistance

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Section: Introductionmentioning

confidence: 98%

Low resistivity contacts to p‐type GaN by plasma treatment

Choi

Jeon

Dawson

2003

phys. stat. sol. (c)

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“…In fact, the high contact resistance of GaN is one of major obstacles to the realisation of long-lifetime operation of GaN-based optical devices. Thus, to develop high-quality Ohmic contacts, different surface treatments using KOH [2], HNO 3 : HCl [3], buffered oxide etch (BOE) [4,5], (NH 4 ) 2 S x [6], and Na 2 S [7] solutions have been employed. Kim et al [3] showed that for Pd/Au Ohmic contacts to p-GaN, the surface treatment with HNO 3 : HCl leads to a specific contact resistance of $10 --4 W cm 2 .…”

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confidence: 99%

Effects of Surface Treatment on the Electrical Properties of Ohmic Contacts to (In)GaN for High Performance Optical Devices

Jang

Park

Seong

2002

phys. stat. sol. (a)

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We investigate the effects of surface treatment on the Ohmic properties of the contacts to p‐GaN and n‐(In)GaN. I–V measurements show that for all the samples, the two‐step surface treatment causes a large reduction in specific contact resistance. The I–V and XPS results show that for the Pt contacts to p‐GaN, the two‐step treatment using a BOE solution results in a reduction of SBH due to the effective removal of native oxide and the shift of the surface Fermi level toward the valence band edge. It is also shown that the two‐step treatment using a HCl solution is very effective in improving the electrical and thermal properties of the Ti/Al contacts to n‐(In)GaN. These results indicate that the two‐step surface treatment can be a promising processing technique for optical devices.

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“…However, it is difficult to obtain p-type Ohmic contacts with low specific contact resistance (q c ) of less than 10 --4 W cm 2 to p-type GaN, because its hole concentration is less than 10 18 cm --3 due to the relatively deep acceptor level of Mg atoms in p-type GaN. To date, there have been various attempts to reduce the contact resistance by surface treatment [1,2] or metal deposition and annealing [3][4][5][6]. These methods have a strong effect in reducing the q c values to the 10 --4 W cm 2 range or less.…”

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confidence: 99%