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RESEARCH PRODUCT
Modification of the sheet resistance under Ti/Al/Ni/Au Ohmic contacts on AlGaN/GaN heterostructures
Monia SperaMonia SperaCorrado BongiornoFabrizio RoccaforteSalvatore Di FrancoGiuseppe GrecoRaffaella Lo NigroCristina MiccoliDomenico CorsoFerdinando Iucolanosubject
Materials scienceAnnealing (metallurgy)Algan gan02 engineering and technology01 natural sciencesMetal0103 physical sciencesAlGaN/GaN heterostructuresGeneral Materials ScienceComposite materialOhmic contactSheet resistanceOhmic contacts010302 applied physicsbusiness.industryMechanical EngineeringContact resistanceTransmission Line ModelHeterojunction021001 nanoscience & nanotechnologyCondensed Matter PhysicsSemiconductorMechanics of Materialsvisual_artvisual_art.visual_art_mediumTi/Al/Ni/Au0210 nano-technologybusinessdescription
This paper reports on the modification of the sheet resistance under Ti/Al/Ni/Au Ohmic contacts on AlGaN/GaN heterostructures, studied by means of Transmission Line Model (TLM) structures, morphological and structural analyses, as well as computer simulations. In particular, the contacts exhibited an Ohmic behaviour after annealing at 800 degrees C, with a specific contact resistance rho(c) = (2.4 +/- 0.2) x 10(-5) Omega cm(2), which was associated to morphological and structural changes of both the metal layer and the interface. Interestingly, TLM analyses gave a value of the sheet resistance under the contact (R-SK = 26.1 +/- 5.0 Omega/rectangle) significantly lower than that measured outside the metal pads (R-SH = 535.5 +/- 12.1 Omega/rectangle). The structural changes observed near the metal/AlGaN interface can be responsible for this electrical modification deduced by TLM analyses. As a matter of fact, two-dimensional TCAD simulation confirmed that the sheet resistance under the contact and the two-dimensional current distribution are affected by the electrical properties of the alloyed metal/semiconductor interface.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2018-05-01 |