Low resistance Ti Ohmic contacts to 4H-SiC by reducing barrier heights without high temperature annealing

Abstract

Ti Ohmic contacts to relatively highly doped (1 × 1018 cm−3) n-type 4H-SiC have been produced, without high temperature annealing, by means of low temperature electronic cyclotron resonance microwave hydrogen plasma pre-treatment (HPT) of the SiC surface. The as-deposited Ti/4H-SiC contacts show Ohmic properties, and the specific contact resistance obtained is as low as 2.07 × 10−4 Ω·cm2 after annealing at low temperatures (400 °C). This is achieved by low barrier height at Ti/SiC interface, which could be attributed to decrease of surface states density by the HPT releasing Fermi level pinning, and to band-gap narrowing, image-force, and thermionic-field emission at high doping.

Enhanced TiC/SiC Ohmic contacts by ECR hydrogen plasma pretreatment and low-temperature post-annealing

“…In this case, q Bn largely depends on q m rather than on interface state density (D it ). [6,13] Fig. 4 shows q Bn as a function of q m (the TiC, Ti, Ni, and Pt contacts [6,16]) for RCA, HPT, and HPT and 600 • C AT.…”

“…[6,13] Fig. 4 shows q Bn as a function of q m (the TiC, Ti, Ni, and Pt contacts [6,16]) for RCA, HPT, and HPT and 600 • C AT. In general, q Bn is expressed as [13] …”

“…In theory, selecting a metal with a low work function (q m ) for n-type semiconductors is an alternative way to reduce q Bn . In practice, however, different q m values are limited to the control of q Bn between the metal and the semiconductor because of the physicochemical nature of the surface before contact and the interfacial chemistry [4,6]. Numerous experiments demonstrated that q Bn reduction improves Ohmic properties through the release of Fermi level pinning (FLP) at the metal/SiC interface, which is controlled by various SiC surface treatments [5,7].…”

Surface-Micromachined Silicon Carbide Pirani Gauges for Harsh Environments

“…Aluminum (Al) and titanium (Ti) were used as metallization materials. Earlier research showed that these metals will form an ohmic contact to the doped poly-SiC layers employed in this work [5], [26], [27]. A post-deposition annealing process in a nitrogen environment was followed to relieve the strain and improve the contact property at the metalsemiconductor interface.…”

Impact of nitrogen plasma passivation on the Al/n-Ge contact

“…While the surface after plasma treatment was more reactivity to adsorb the atmospheric oxygen atoms to form GeOx. Interface states caused by the contaminants [26] and dangling bonds [27,28], were proposed to be responsible for the severe FLP effect in the metal/Ge contacts. The contaminants were removed and some dangling bonds was occupied by O atoms, hence, the SBH was lowered, as shown in Fig.…”