Very low specific contact resistance measurements made on a highly p-type doped 4H-SiC layer selectively grown by vapor-liquid-solid transport

Abstract

This work reports on the performances of ohmic contacts fabricated on highly p-type doped 4H-SiC epitaxial layer selectively grown by vapor-liquid-solid transport. Due to the very high doping level obtained, the contacts have an ohmic behavior even without any annealing process. Upon variation of annealing temperatures, it was shown that both 500 and 800 °C annealing temperature lead to a minimum value of the Specific Contact Resistance (SCR) down to 1.3×10−6 Ω⋅cm2. However, a large variation of the minimum SCR values has been observed (up to 4×10−4 Ω⋅cm2). Possible sources of this fluctuation have been also discussed in this paper

A Study on the Temperature of Ohmic Contact to p-Type SiC Based on Ti3SiC2Phase

“…Such contacts are generally employed containing aluminum [6], and while many different alloys have been investigated, a great deal of attention has been focused on Al-Ti [5], [7]- [10], which has demonstrated specific contact resistances (SCRs) on the order of 10 −3 -10 −5 · cm 2 on p-type SiC. Another investigation has focused on the Ni/Ti/Al contact fabricated on highly p-type 4H-SiC [11] leading to low SCR (2.8 × 10 −6 · cm 2 ), but this result was not reproducible.…”

“…XTEM-BF image taken along the[11]-[20] SiC zone axis showing that (a) after annealing of Ti 30 Al 70 at 1000°C, Ti 3 SiC 2 completely covers the surface of the SiC and is itself covered by an Al layer and (b) after annealing of Ti at 1200°C, modified SiC covers the surface of the SiC and is itself covered by a Ti 3 SiC 2 layer.…”

An exact field solution of contact resistance and comparison with the transmission line model

“…7 as a function of a/h 2 and r c ¼ q c /q 2 h 2 . Symbols represent previous experiments: ᭺ for Au/Ge-GaAs, 10 ᭛ for Cu-Graphite, 4 þ for Al-Si, 1 D for Ag-Si/TiOx, 11 ( for Ag-Si, 11 Â for Ti/Al/Ni/Cu-AlGaN/GaN, 12 and * for SiC-p þþ -SiC-n. 13…”

A Study on the Chemistry of Epitaxial Ti₃SiC₂ Formation on 4H-SiC Using Al-Ti Annealing

“…This is known to be especially difficult on p-type SiC. Rather good results have been obtained from high-temperature annealed Ti and Al-containing alloys [1][2][3][4][5]. The reason why these alloys display low contact resistance is still under discussion though the beneficial effect of the resulting MAX phase Ti 3 SiC 2 is often suggested [6,7].…”