Interfacial microstructure and electrical properties of the Pt/Ti ohmic contact in <i>p</i>-In0.53Ga0.47As formed by rapid thermal processing

Chu, S. N. G.; Katz, A.; Boone, T.; Thomas, Peter; Riggs, V. G.; Dautremont‐Smith, W. C.; Johnston, W. D.

doi:10.1063/1.345018

Cited by 49 publications

(15 citation statements)

References 17 publications

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“…Deposition of Au prior to annealing permits deposition of all the metal layers in one sequence, without breaking the vacuum, although Au may reduce contact stability during subsequent annealing. The Pt and Ti layers serve to improve adhesion to the underlying semiconductor and act as a diffusion barrier for Au [3]. Good contacts to a number of semiconductors have been obtained using this scheme, with contact resistance values depending very much upon the initial doping levels in the semiconductors.…”

Section: Introductionmentioning

confidence: 91%

“…At this temperature, there is significant interdiffusion between the Pt and Ti layers, resulting in a layer with a somewhat larger grain size relative to the as-deposited condition, i.e. 56 nm versus 11 nm [3,14]. No further grain growth occurs at higher temperatures.…”

Section: Introductionmentioning

confidence: 97%

“…One type of contact to InP-based semiconductors receiving considerable attention in the literature in recent years involves the use of Ti and Pt layers, with or without an Au capping layer, deposited sequentially on the semiconductor [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]16]. Gold, which can be deposited either before or after contact annealing, is needed to permit wire bonding and solder bonding of the device to a suitable submount [2].…”

Section: Introductionmentioning

confidence: 99%

“…Although many papers have been written describing the electrical and stress behaviour of Pt/Ti-based contacts, very little has been done to characterize the microstructural changes that occur during annealing. The analysis that has been done is mainly by Katz and co-workers [1][2][3][4][5][6][7][8][9][11][12][13][14]. Most of their analysis has involved Auger electron spectroscopy (AES) or Rutherford backscattering spectroscopy (RBS), with a limited amount of transmission electron microscopy (TEM).…”

Section: Introductionmentioning

confidence: 99%

“…There is also significant interaction between Ti and the underlying semiconductor, leading to Ti in-diffusion and In and As out-diffusion. The reacted zone at the interface consists of a "defective interfacial layer (or "deformed" InGaAs-deformed in this case refers to Ga-rich InGaAs) and solid state regrown second phase regions" [3,14]. The "second phase region" has not been conclusively identified, although the authors speculate that it may be made up of any number of the following intermetallics: InAs, InTi3, Ga3Pts, GaPt, Ti2Ga3, In2Pt and GaPt3 [1,3,14].…”

Section: Introductionmentioning

confidence: 99%

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Microstructural analysis of Au/Pt/Ti contacts to p-type InGaAs

Ivey

Jian

Bruce³

et al. 1995

J Mater Sci: Mater Electron

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A detailed study on the microstructural changes that occur on annealing of Au/Pt/Ti ohmiic contacts to n-type InGaAs has been carried out. The metal layers were deposited sequentially by electron beam evaporation onto InGaAs, doped with Zn to a level of 7 x 1018 cm -3, that was epitaxially grown on ( 1 0 0~> InP substrates. The deposition sequenc.e and metal layer thicknesses were: Ti (25 or 30 nm), Pt (25 or 30 nm) and Au (250 or 300 nm). Samples were annealed at temperatures ranging from 250-425 °C in a nitrogen atmosphere. As-deposited contacts were Schottky barriers, while a minimum contact resistance of 2 × 10 -5 O cm 2 was obtained by annealing in the 375-425 °C range. Annealing resulted in the inward diffusion of Ti and outward diffusion of In and As, leading to the formation of TiAs, metallic In and Ga-rich InGaAs at the Ti/InGaAs interface. The Pt diffusion barrier was effective in preventing In diffusion into the outer Au layer and minimizing Au diffusion to the semiconductor. IntroductionDuring device operation, electrical communication links between the active regions of semiconductor devices and the external circuit are provided by metal/ semiconductor contacts. Ohmic contacts on InPbased materials are essential for electronic devices such as field effect transistors (FET), junction field effect transistors (JFET), high electron mobility transistors (HEMT) and heterojunction bipolar transistors (HBT), as well as for photonic devices, such as long-wavelength laser diodes, light-emitting diodes (LED) and photoelectronic and solar cells. Semiconductor devices are being continually scaled down in size, and operated at higher current density and elevated temperature, placing ever-increasing demands on ohmic contact performance. The main ohmic contact requirements are low contact resistance and high thermal stability, both of which are affected by the metallization microstructures, as well as good adhesion and a shallow reacted zone at the metallization/semiconductor interface. It is essential to understand the relationship between the microstructure and the electrical properties of the metal/semiconductor contacts in order to fabricate high-quality and reliable ohmic contacts. Transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy is one of the best techniques to monitor and analyse the microstructural changes that occur during annealing. It allows direct observation of interfaces and provides both crystallographic and chemical composition information with high spacial resolution in three dimensions.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 97%