Abstract
This thesis study about optoelectric properties and thermal stability of p-GaN reflective ohmic contacts Sn (2nm) / Ag (150nm), AgSn (2 at%), AgCu (4 at%) and AgCu (8 at%) four specimens which are prepared by due electron guns evaporation and AgCu (T.E.) prepared by thermal evaporation plus a AgCu(S.E.) prepared by single electron gun evaporation six specimens in total. We discuss the effect, including light reflectivity, sheet resistance of the metal thin film, specific contact resistance and thermal stability, on the optoelectric properties of AgSn and AgCu alloy reflective ohmic contacts, be influence by different alloy composition, different annealing methods, including furnace annealing and rapid thermal annealing, and different deposition process. We found that Sn (2nm) / Ag film can inhibit the aggregation of Ag film at high temperature annealing, and there are no aggregation be found on AgSn and AgCu thin film after furnace annealing and rapid thermal annealing, and after aging at 400 ℃ for one hour, the influence on reflectivity, sheet resistance of the metal thin film and specific contact resistance are very small. Comprehensive consideration above-mentioned properties, AgSn (2 at%) and AgCu (4 at%) alloys thin films are excellent. After anneal 5min in air at 500 ℃, the AgSn(2 at%) reflectors produce low specific contact resistance(1.2 × 10-3 Ω-cm2),and even lower after aging(7 × 10-4 Ω-cm2), high reflectivity(102% at 460nm),good sheet resistance of the metal thin film(0.15 Ω/□), and good thermal stability. After anneal 5min in air at 500 ℃, the AgCu(4 at%) reflectors produce low specific contact resistance(8.2 × 10-4 Ω-cm2),and even lower after aging(5.5 × 10-4 Ω-cm2), high reflectivity(102% at 460nm),good sheet resistance of the metal thin film(0.12 Ω/□), and good thermal stability.