Optical and electrical properties study on p-type conducting CuAlS2+x with wide band gap

A series of wide band gap semiconductors, CuAlS2+x, with a chalcopyrite structure were synthesized in bulk form by spark plasma sintering. p-type conductions for all samples were confirmed by positive Seebeck and Hall coefficients. For excess S introduced into the system, the carrier concentration was highly enhanced, reaching 6.9 × 1019 cm−3 for the 10% doped sample, which results in a high conductivity of 4.6 S cm−1 without decreasing the bang gap.