Inductively-coupled-plasma reactive ion etching of ZnO using BCl3-based plasmas and effect of the plasma treatment on Ti/Au ohmic contacts to ZnO

Contacts to ZnO

“…The usual approaches involve surface cleaning to reduce barrier height or increase of the effective carrier concentration of the surface through preferential loss of oxygen [19,20]. Specific contact resistances of $3 Â 10 À4 O cm À3 were reported for Pt-Ga contacts on n-ZnO epitaxial layers [19,21], 2 Â 10 À4 O cm À3 for Ti/Au on Al-doped epitaxial layers [25,26], 0.7 O cm À3 for non-alloyed In on laserprocessed n-ZnO substrates [27], 2.5 Â 10 À5 O cm À3 for non-alloyed Al on epitaxial n-type ZnO [28] 4.3 Â 10 À5 O cm À3 for Ti/Au on plasma exposed, Al-doped n-type epitaxial ZnO [29,30] and 9 Â 10 À7 O cm À3 for Ti/Al on n + -epitaxial ZnO [31,32]. Several points are clear from the past works, namely that the minimum contact resistance generally occurs for post-deposition annealing temperatures of 200-300 1C on doped samples which must be treated so as to further increase the near-surface carrier concentration.…”

Controlled Chemical Etching of ZnO Film for Step Coverage in MEMS Acoustic Sensor

“…A number of dry etching techniques have been reported for fine patterning of ZnO layers [7]. However, a metal mask is required in these techniques to etch the ZnO layer, because photoresist is decomposed when exposed to plasma for long durations.…”

Al/Au ohmic contact to n-ZnO by dc sputtering

“…A lot of metallization schemes, such as Ti/Au, Al/Pt, Ti/Al/Pt/Au, and Al, were investigated as ohmic contact materials for n-ZnO [9][10][11][12]. These contact materials were mainly deposited by using an electron beam method [8][9][10][11][12]. The minimum contact resistance was generally obtained after annealing at 200-300 • C, which increased the carrier concentration near the surface of n-ZnO.…”