Analysis of surface roughness in Ti/Al/Ni/Au Ohmic contact to AlGaN/GaN high electron mobility transistors

Gong, Rumin; Wang, Jinyan; Liu, Shenghou; Dong, Zhihua; Yu, Min; Wen, Cheng P.; Cai, Yong Q.; Zhang, Baoshun

doi:10.1063/1.3479928

Cited by 94 publications

(50 citation statements)

References 13 publications

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“…At such high temperatures, the sheet resistance (R sh ) of the GaN based heterostructures can increase, 10,11 which may lead to higher on-state resistance (R on ) and limit the current delivery capability of transistors. 13,14 The rough surface may cause reproducibility and reliability issues, especially in highly scaled devices. 12 The high annealing temperature also causes the balling of molten Al due to its low melting point (660 C), which leads to a rough contact surface.…”

Section: Introductionmentioning

confidence: 99%

Low thermal budget Hf/Al/Ta ohmic contacts for InAlN/GaN-on-Si HEMTs with enhanced breakdown voltage

Liu¹,

Singh²,

Ngoo³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Articles you may be interested inTi/Al/Ti/Ni/Au ohmic contacts on AlGaN/GaN high electron mobility transistors with improved surface morphology and low contact resistanceThe authors have studied the electrical characteristics of Hf/Al/Ta ohmic contacts on In 0.18 Al 0.82 N/GaN heterostructure grown on Si (111) substrate. With annealing at 600 C in vacuum (which is $200 C lower than that for traditional Ti/Al/Ni/Au contacts), a minimum ohmic contact resistance of $0.58 XÁmm and specific contact resistivity of $6.75 Â 10 À6 XÁcm 2 are obtained. The minimum contact resistance of Hf/Al/Ta contacts is comparable to that of Ti/Al/Ni/Au contacts. Owing to the lower annealing temperature, Hf/Al/Ta contacts exhibit better surface morphology and edge acuity. More importantly, Hf/Al/Ta contacts show a smooth interface with In 0.18 Al 0.82 N/GaN, whereas spike structures that penetrate the In 0.18 Al 0.82 N layer are observed for Ti/Al/Ni/Au contacts. As a result, the source-carrier-injection induced breakdown mechanism is reduced in the In 0.18 Al 0.82 N/GaN-on-Si high electron mobility transistors (HEMTs) with Hf/Al/Ta ohmic contacts, thereby leading to an improved three-terminal off-state breakdown voltage by about 100 V ($53.5% improvement), in comparison to Ti/Al/Ni/Au based HEMTs.

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Section: Introductionmentioning

confidence: 99%

Low thermal budget Hf/Al/Ta ohmic contacts for InAlN/GaN-on-Si HEMTs with enhanced breakdown voltage

Liu¹,

Singh²,

Ngoo³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…The as-deposited (not annealed) sample showed a rectifying character. The van der Pauw Hall mobility measurement showed that the sheet density of carriers beneath the metal contacts remained on the same level of 9×10 12 cm…”

Section: Resultsmentioning

confidence: 99%

Study of interface reactions between Ti/Al/Ni/Au metallization and AlGaN/GaN heterostructures

Macherzyński

Paszkiewicz

2013

Open Physics

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Abstract:The electrical characteristics, and the range of interface metal-semiconductor reactions of Ti/Al/Ni/Au metallization with AlGaN/GaN heterostructures at various annealing temperatures ranging from 715 • C to 865 • C, have been investigated. The relation between the depth of the interface solid state reaction and the current-voltage (I-V) characteristics of the ohmic contact, have been studied. It was observed, that the transition from nonlinear to linear I-V behaviour occurred after the annealing at 805 • C. The structural changes in AlGaN/GaN heterostructures beneath the metallic contact after the thermal treatment, were investigated. After removing the metallization by etching, the atomic force microscope profiles and scanning electron microscope images, were studied to define the depth to which the interfacial solid state reactions between the metallization and the semiconductor structure take place. It was observed, that the changes in the heterostructures, caused by the interface m-s reactions, were observed up to a depth of 180 nm at 865 • C. In the worst case, this could result in the complete removal of the two-dimensional electron gas under the metallization of the ohmic contacts. To study the influence of the annealing process parameters on the properties of the two-dimensional electron gas, the van der Pauw Hall mobility measurement was performed.PACS (

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“…Therefore, a smooth surface morphology must be guaranteed because it closely related with an excellent ohmic contact. 30,31 Fig. 7 shows the typical AFM surface morphology images of 5 Â 5 lm 2 scan area for two structures, respectively.…”

Section: E Afm Characterizationmentioning

confidence: 99%

Dislocation blocking by AlGaN hot electron injecting layer in the epitaxial growth of GaN terahertz Gunn diode

Yang

Zhang

et al. 2013

Journal of Applied Physics

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This paper reports an efficient method to improve the crystal quality of GaN Gunn diode with AlGaN hot electron injecting layer (HEI). An evident reduction of screw dislocation and edge dislocation densities is achieved by the strain management and the enhanced lateral growth in high temperature grown AlGaN HEI layer. Compared with the top hot electron injecting layer (THEI) structure, the bottom hot electron injecting layer (BHEI) structure enhances the crystal quality of transit region due to the growth sequence modulation of HEI layer. A high Hall mobility of 2934 cm2/Vs at 77 K, a nearly flat downtrend of Hall mobility at the temperature ranging from 300 to 573 K, a low intensity of ratio of yellow luminescence band to band edge emission, a narrow band edge emission line-width, and a smooth surface morphology are observed for the BHEI structural epitaxy of Gunn diode, which indicates that AlGaN BHEI structure is a promising candidate for fabrication of GaN Gunn diodes in terahertz regime.

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Analysis of surface roughness in Ti/Al/Ni/Au Ohmic contact to AlGaN/GaN high electron mobility transistors

Cited by 94 publications

References 13 publications

Low thermal budget Hf/Al/Ta ohmic contacts for InAlN/GaN-on-Si HEMTs with enhanced breakdown voltage

Low thermal budget Hf/Al/Ta ohmic contacts for InAlN/GaN-on-Si HEMTs with enhanced breakdown voltage

Study of interface reactions between Ti/Al/Ni/Au metallization and AlGaN/GaN heterostructures

Dislocation blocking by AlGaN hot electron injecting layer in the epitaxial growth of GaN terahertz Gunn diode

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