P-Type Transparent Conductivity of Cu<sub>1-x</sub>AlS<sub>2</sub> (x = 0 ~ 0.08)

A series of Cu1-xAlS2 (x = 0 ~ 0.08) bulk samples were synthesized by spark plasma sintering. The electrical and optical properties were investigated. P-type conductions for all samples were confirmed by both positive Seebeck coefficient and Hall coefficient. Bulk undoped CuAlS2 had a high conductivity of about 0.9 S/cm with a large band gap of 3.4 eV at room temperature. For vacancy-doped in Cu site, the carrier concentration was highly enhanced, reaching 1.7 × 1019 cm-3 for 8 mol% doped sample, and without decreasing the bang gap. The introduction of vacancies destroys the continuity of Cu-S network, which decreases the Hall mobility.