A study of the Au/Ni ohmic contact on p-GaN

Abstract

Disorder induced semiconductor to metal transition and modifications of grain boundaries in nanocrystalline zinc oxide thin film J. Appl. Phys. 112, 073101 (2012) Control of normal and abnormal bipolar resistive switching by interface junction on In/Nb:SrTiO3 interface Appl. Phys. Lett. 101, 133506 (2012) Cross-plane electronic and thermal transport properties of p-type La0.67Sr0.33MnO3/LaMnO3 perovskite oxide metal/semiconductor superlattices J. Appl. Phys. 112, 063714 (2012) Polarization Coulomb field scattering in In0.18Al0.82N/AlN/GaN heterostructure field-effect transistorsThe formation mechanism of the ohmic Au/Ni/p-GaN contact has been investigated. We found that it is essential to ͑i͒ deposit a structure of Au and Ni in the proper deposition sequence, and ͑ii͒ anneal the bilayer structure in an oxygen containing ambient. Our findings indicated that oxygen assists the layer-reversal reactions of the metallized layers to form a structure of NiO/Au/p-GaN.

X-ray photoemission determination of the Schottky barrier height of metal contacts to n–GaN and p–GaN

“…Contacts to p-type GaN have been particularly challenging, since it is difficult to grow samples with a high enough carrier concentration to promote field emission through the Schottky barrier. Due to the complexity of metallurgical contacts, various approaches have been tried, including chemical surface treatments, [3][4][5][6][7] plasma cleaning, [8][9][10] metal deposition techniques ͑sputtering, electron beam, or thermal deposition͒, [11][12][13] contact annealing in a variety of ambients, 14,15 and use of bilayers 16 -18 or multilayers [19][20][21] of various metals.…”

Oxidation treatment on Ni/Au Ohmic contacts to p‐type GaN

“…On the other hand, the schemes of NiO/p-GaN [9] and Au/NiO/p-GaN [3,4] did not show a low-resistance Ohmic contact. It was reported that the prefabricated NiO layer prevented interdiffusion and metallurgic reaction of Ni, Au, N, Ga [10][11], and alleviated the reversion reaction from Au/Ni/GaN to NiO/Au/GaN [3,4]. These reactions were believed to be important for the formation of p-GaN Ohmic contacts.…”

“…Ho et al suggest that the formation of p-NiO by oxidizing the Ni layer leads to a reduction of the Schottky barrier height (SBH) of the Ni/Au contact to p-GaN, and the granular Au particles in the NiO matrix form a high conductive cermet-like matter [1]. On the other hand, the schemes of NiO/p-GaN [9] and Au/NiO/p-GaN [3,4] did not show a low-resistance Ohmic contact. It was reported that the prefabricated NiO layer prevented interdiffusion and metallurgic reaction of Ni, Au, N, Ga [10][11], and alleviated the reversion reaction from Au/Ni/GaN to NiO/Au/GaN [3,4].…”

“…However, the role of oxidation in thermal annealing in the formation of p-GaN Ohmic contacts has not been clarified [1,[3][4]. Ho et al suggest that the formation of p-NiO by oxidizing the Ni layer leads to a reduction of the Schottky barrier height (SBH) of the Ni/Au contact to p-GaN, and the granular Au particles in the NiO matrix form a high conductive cermet-like matter [1].…”

Comment on “Low-resistance ohmic contacts to p-type GaN achieved by the oxidation of Ni∕Au films” [J. Appl. Phys. 86, 4491 (1999)]

“…Using the parameters shown in Table 1 JOURNAL OF APPLIED PHYSICS VOLUME 96, NUMBER 8bilayer may be caused by some combined factors other than a "small barrier height at the p-NiO/ p-GaN interface." 7,8 …”