Development and characterisation of TiC ohmic contacts for n-type SiC

TiC ohmic contact metallization to n-type {dollar}beta{dollar}-SiC and 6H{dollar}alpha{dollar}-SiC was developed and characterized. TiC was deposited using dc sputtering and chemical vapor deposition.; A metal-organic chemical vapor deposition (MOCVD) system, with an inverted vertical reactor, was designed and built. A MOCVD process using a single reactant source (1,2-disilylethane or {dollar}rm Sisb2Csb2Hsb{lcub}10{rcub}{dollar}) was optimized and used to grow single crystal SiC on TiC substrates. The epilayers had a smooth morphology and were free of double positioning boundaries, antiphase domains and stacking faults. NH{dollar}sb3{dollar} was used for in-situ nitrogen doping. In-situ B doping for isolation layers was achieved by {dollar}rm Bsb2Hsb6{dollar}. Epitaxial CVD TiC was grown on SiC using TiCl{dollar}sb4{dollar} and {dollar}rm Csb2Hsb4{dollar} sources. Sputtering system was built and TiC sputter deposition was developed.; Transfer length method was used to measure the specific contact resistance ({dollar}rhosb{lcub}rm c{rcub}{dollar}), sheet resistance of n-type SiC ({dollar}rhosb{lcub}rm s{rcub}{dollar}) and contact resistance ({dollar}rm Rsb{lcub}c{rcub}{dollar}) of TiC ohmic contacts. TLM test structures were fabricated using photolithography, reactive ion etching (SF{dollar}sb6{dollar}) and wet etching.; The {dollar}rhosb{lcub}rm c{rcub}{dollar} values obtained are the lowest ever reported for ohmic contacts to n-type SiC. Average {dollar}rhosb{lcub}rm c{rcub}{dollar} obtained for epitaxial TiC contacts on n{dollar}sp+{dollar}({dollar}rm 4times 10sp{lcub}19{rcub} cmsp{lcub}-3{rcub}{dollar}) 6H{dollar}alpha{dollar}-SiC was {dollar}rm 1.30 times 10sp{lcub}-5{rcub} Omega .cmsp2{dollar} and for sputtered TiC contacts = {dollar}rm 2.89 times 10sp{lcub}-5{rcub} Omega .cmsp2{dollar}. The {dollar}approx{dollar}55% lower {dollar}rhosb{lcub}rm c{rcub}{dollar} for epitaxial contacts compared to that of sputtered contacts suggests that epitaxial ohmic contacts are more ideal Schottky barriers. For epitaxial TiC contacts on n{dollar}sp+{dollar}({dollar}rm 2 times 10sp{lcub}19{rcub} cmsp{lcub}-3{rcub}{dollar}) {dollar}beta{dollar}-SiC, {dollar}rhosb{lcub}rm c{rcub}{dollar} was {dollar}rm 5.44 times 10sp{lcub}-6{rcub} Omega .cmsp2{dollar} which is 60% lower than for CVD TiC/n{dollar}sp+{dollar} 6H{dollar}alpha{dollar}-SiC contacts. The comparative value is in accordance with superior transport properties of {dollar}beta{dollar}-SiC.; Cross-sectional transmission electron microscopy of CVD TiC/SiC interface did not show presence any third phases or interdiffusion. Contact resistance remained unaffected after subjecting the contacts to high current density conditions for one hour. Excellent hardness and adhesion was shown by all contacts.