Nickel Ohmic Contacts to N-Implanted (0001) 4H-SiC

Li, M.; Ahyi, A. C.; Zhu, Xingguang; Chen, Zengjun; Isaacs-Smith, T.; Williams, John R.; Crofton, J.

doi:10.1007/s11664-010-1128-1

Cited by 9 publications

(13 citation statements)

References 15 publications

(13 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is most likely caused by the saturation of free donors in 3C-SiC [27], which means a higher concentration of active N donors is physically impossible even with higher annealing temperatures or longer time periods. There is almost no difference between capped and uncapped samples in high dose case, even with a bigger surface roughness difference (3.6nm difference) and much more obvious resistance, which is known to be heavily dependent on the semiconductor doping level [5]. It was later found out the low dose sample contact resistance was one order of magnitude higher than the high dose and medium dose ones (not shown here).…”

Section: Room Temperature IV Measurementsmentioning

confidence: 71%

“…It can be noticed that regardless of the dose levels, all groups experienced a surface degradation, although the high dose sample surfaces were degraded more severely, indicating higher lattice damage [5,18]. The SiO 2 capped samples were left with a higher roughness compared with the uncapped ones in all batches.…”

Section: Surface Roughness Evolutionmentioning

confidence: 91%

“…Due to the low diffusion coefficients of dopants in SiC, highly doped layers are mostly obtained by selective ion-implantation, and after that a high temperature (1400~1700°C) [5] PIA process is usually applied to repair the lattice damage induced by implantation, which can otherwise degrade the semiconductor layer electrical properties [6]. A roughened surface, enhanced at implanted regions, often emerges after PIA and can deteriorate the SiC interface performance such as the Schottky contact and FET channel [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Sharma

Shah

et al. 2015

Applied Surface Science

View full text Add to dashboard Cite

A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the bandgap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ~6x10 20 cm -3 at 20K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5x10 19 cm -3 , donor level 15meV) to ~12% for 6x10 20 cm -3 . Free donors are found to saturate in 3C-SiC at ~7x1019 cm -3 . The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO 2 layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (~1.4mΩ.cm) has been observed for medium doped (4x10 19 cm -3) sample with PIA 1375°C 2h without a SiO 2 cap.Keywords: 3C-SiC; post-implantation activation; Van der Pauw; Hall; degenerated film IntroductionSilicon carbide (SiC) has been considered as the future power devices materials attributed to its superior electrical, mechanical and thermal properties. 3C-SiC has a smaller bandgap (2.3eV) than 4H-SiC (3.2eV), but still 2 times higher than Si (1.1eV) and can be grown directly on large area Experimental ProceduresThe materials studied in this work was a 10μm thick unintentionally doped (<1x10 16 cm -3 ) 3C-SiC film epitaxial grown on a 4 inch Si(100) substrate by NOVASiC. The wafer went through a chemical-mechanical polishing process [20] after the CVD growth with an initial surface RMS roughness ~0.2nm determined from atomic force microscopy (AFM) measurements. A Veeco multimode AFM with Nanonis controller was used to evaluate the surface roughness. The overall roughness value was determined by scanning three 10x10μm 2 areasand averaging the results. The wafer was cut into 30 8x8mm 2 pieces and equally divided into 3 batches. An onaxis nitrogen implantation process was conducted on the plain surface of all samples at room temperature. A series of energies with increasing total doses were applied during implantation to form box profile at 3 doping levels, which will be called high dose, medium dose and low dose samples in following text. Nitrogen was selected as the dopant rather than phosphorous since it does less damage to the 3C-SiC film [17,18] SIMS profilesAfter the PIA process, Second Ion Mass Spectrometry (SIMS) analysis was conducted on samples from each dose batch for the toughest PIA condition (1375°C, 2 hours) as shown in Fig 2. The profiles before PIA were not shown here but were expected to be much like the annealed ones due to the unlikely observable diffusion of nitrogen in 3C-SiC below 1800°C [17,24]. High dose and medium dose samples both achieved an implantation depth of ~300nm with peak values around 6x10 20 cm -3 and 4x10 1...

show abstract

Section: Room Temperature IV Measurementsmentioning

confidence: 71%

Section: Surface Roughness Evolutionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Sharma

Shah

et al. 2015

Applied Surface Science

View full text Add to dashboard Cite

show abstract

“…The temperature required for SiC post-implantation activation (PIA) is very high that above 1400°C [9,10] is common for n-type and even higher (>1600°C) for p-type [11][12][13] since acceptors generally sit deeper in the band gap than donors, namely, more difficult to activate. This high temperature means conventional quartz tubes are not up to the task and high melting point tubes made of Al 2 O 3 and SiC or similar have to be used.…”

Section: Thermal Diffusion and Ion Implantationmentioning

confidence: 99%

Main Differences in Processing Si and SiC Devices

Li¹,

Jennings²

2018

Disruptive Wide Bandgap Semiconductors, Related Technologies, and Their Applications

View full text Add to dashboard Cite

Due to the different physical properties of Si and SiC, many conventional Si device processing techniques cannot be directly transferred to SiC device fabrication. To deliver high-performance SiC commercial power devices, new techniques quite different from Si industry were developed in past decades for processing device, such as dopant implantation, metal contact, MOS interface, etc. On the other hand, the physics model behind many of these SiC processing technologies is not updated in the same pace that the success of them can still not be fully understood.The activation of dopants in 4H-SiC has been intensively studied, and the efforts are mainly put into two directions, namely, protecting the semiconductor surface morphology while at the same time maximising the active concentration of implanted dopants. Figure 1. Schematic graph showing a typical dopant thermal diffusion process using a gas source. Main Differences in Processing Si and SiC Devices

show abstract

“…Ni has been widely used for this purpose [44][45][46][47] based on the same process method discussed above. The annealing process-step for this element results in the formation of silicide phases in the contact, which are Ni2Si, NiSi, or Ni31Si12.…”

Section: Ni-based Ohmic Contacts To 4h-sicmentioning

confidence: 99%

Novel Layered and 2D Materials for Functionality Enhancement of Contacts and Gas Sensors

Fashandi¹

View full text Add to dashboard Cite

IIThe cover image shows partial intercalation of gold (in yellow) into Ti3SiC2 observed by scanning transmission electron microscopy; a result from my research.During the course of research underlying this thesis, I was enrolled in Agora Materiae, a multidisciplinary doctoral program at Linköping University, Sweden. AbstractChemical gas sensors are widely-used electronic devices for detecting or measuring the density levels of desired gas species. In this study, materials with established or potential applications for gas sensors are treated. For the case of high-temperature applications (≈600 °C), semiconductor-based gas sensors suffer from rapid oxidation of the metallic ohmic contacts, the same cause-of-failure as for the general case of high-temperature semiconductor electronics. 4H-SiC is an ideal semiconductor for high-temperature applications. Ti3SiC2 is a known ohmic contact to 4H-SiC with the known two-step synthesis process of post-annealing of pre-deposited Ti/Al multilayers or sputterdeposition of Ti3SiC2 films at > 900 °C. Here, sputter-deposition of Ti on 4H-SiC at > 900 °C is presented as a novel single-step method for the synthesis of Ti3SiC2 ohmic contacts, based on a concurrent reaction between sputter-deposited Ti and 4H-SiC.Ti3SiC2, similar to any other known ohmic contact, degrades rapidly in high-temperature oxidizing ambient. To try to overcome this obstacle, noble-metal diffusion into Ti3SiC2 has been studied with the goal to retain ohmic properties of Ti3SiC2 while taking advantage from the oxidation resistivity of noble metals. A novel exchange intercalation between Ti3SiC2 and Au is discovered which results in almost complete exchange of Si with Au giving rise to novel Ti3AuC2 and Ti3Au2C2. Ti3IrC2 is also synthesized through exchange intercalation of Ir into Ti3Au2C2. All the aforementioned phases showed ohmic properties to 4H-SiC. This technique is also studied based on Ti2AlC and Ti3AlC2 resulting in the synthesis of novel Ti2Au2C and Ti3Au2C2, respectively. Using Ti3AuC2and an IrOx/Au capping layer, an ohmic contact was manufactured which maintained ohmic properties and showed no structural defects after 1000 h of aging at 600 °C air. Growth of monolayer iron oxide on porous Pt sensing layers is another novel approach used in this study for applying the unique properties of 2D materials for gas sensors. A low temperature shift in CO oxidation characteristics is presented as compared to bare Pt.The approach is similar to that previously reported using bulk single-crystal Pt substrate, My contributions: I was involved in planning. I performed the depositions, XRD, SEM, EDX, and TEM sample preparations. I wrote the manuscript with P.E. Paper 2 Submitted for publicationMy contributions: I was involved in planning. I preformed the sensing measurements and wrote the manuscript together with M.A., with contributions from coauthors on the parts related to the photo electron spectroscopy and the monolayer synthesis process.XIII

show abstract

Nickel Ohmic Contacts to N-Implanted (0001) 4H-SiC

Cited by 9 publications

References 15 publications

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Main Differences in Processing Si and SiC Devices

Novel Layered and 2D Materials for Functionality Enhancement of Contacts and Gas Sensors

Contact Info

Product

Resources

About