Improved Ni Schottky Contacts on n-Type 4H-SiC Using Thermal Processing

Abstract

High-temperature processing was used to improve the barrier properties of three sets of n-type 4H-SiC Schottky diodes fabricated with Ni Schottky contacts. We obtained an optimum average barrier height of 1.78 eV and an ideality factor of 1.09 using current-voltage measurements on diodes annealed in vacuum at 500°C for 24 h. Nonannealed contacts had an average barrier height of 1.48 eV and an ideality factor of 1.85. The Rutherford backscattering spectra of the Ni/SiC contacts revealed the formation of a nickel silicide at the interface, accompanied by a substantial reduction in oxygen following annealing.

Effects of deposition temperature on the electrical properties of Ti/SiC Schottky barrier diodes

“…This material was supplied by Cree, Inc. and a full description of the wafer surface preparation and back-side ohmic contact preparation carried can be found in Ref. 15. On the front (epilayer) side of the samples, about 200 nm-thick Ti film was deposited at different temperatures (28 o C, 200 o C, 400 o C, 500 o C, 700 o C and 900 o C) from a 99.995% purity 2-inch target through a stainless steel shadow mask consisting of circular holes of 600 µm in diameter.…”

“…8 Our group previously reported improvement of SiC Schottky diodes by depositing various metal contacts at elevated temperatures. [15][16][17] Improvements in the contacts were explained in terms of removal of unwanted oxides at the interface and the formation of silicides with higher work functions. In this paper, we investigated the effect of Ti Schottky contact deposition temperature on the Ti/SiC Schottky barrier diodes, which, as far as we know, has not yet been conducted.…”

Thermally annealed gamma irradiated Ni/4H-SiC Schottky barrier diode characteristics

“…In the literature, thermal annealing effects on non-irradiated 4H-SiC SBDs (i.e. changes in electrical character-istics and trap signatures) are extensively analyzed [11,12,[16][17][18][19][20][21][22][23][24][25][26][27][28][29] . However, the annealing effects on gamma irradiated 4H-SiC SBD characteristics have not yet been examined.…”

Electrical Characterization of High Energy Electron Irradiated Ni/4H-SiC Schottky Barrier Diodes

“…[1][2][3] These properties make SiC a suitable semiconductor for fabrication of devices that can operate at high power, high frequency and high temperatures. 2,3 Additionally, SiC is also a radiation hard material and this makes it a suitable semiconductor for devices that can operate both in high radiation environments and at high temperatures. 4,5 Although it is radiation hard, SiC is not totally resistant to irradiation damage.…”