共掺杂Cu,Te后禁带宽度变窄对In_2Se_3基半导体热电性能的影响

Effect of Band Gap Reduction on the Thermoelectric Properties of In_2Se_3 Based Semiconductors after Co-Doping of Cu and Te

α-In2Se3是一类A2ⅢB3Ⅳ型宽带隙半导体材料。但在α-In2Se3化合物中共掺杂适量的Cu,Te后发现禁带宽度(Eg)变窄,Eg值由本征态时的1.32eV减小到1.14eV。掺杂后电学性能得到了大幅度的改善。最大功率因子由0.7610-4增大到2.810-4W·m-1·K-2;最大热电优值(ZT)从本征态时的0.25提高到0.63。高分辨电镜(HRTEM)观察结果表明,在未掺杂时,α-In2Se3呈现非晶状组织,共掺杂Cu,Te后,微结构则转变成明显的多晶组织。在温度高于500K时,掺杂后晶格热导率的适量提高与该微结构转变有直接联系。

-In2Se3 is one of the A2ⅢB3Ⅳ type semiconductors with a wide band gap. A proper co-doping of Cu and Te leads to the formation of slab Cu2Se, which accounts for the reduction of band gap Eg , with its value decreasing from 1.32 eV for the intrinsic -In2Se3 to 1.14 eV. This reduction of band gap is responsible for the remarkable improvement in thermoelectric properties, with the maximum power factor p increasing from 0.76×10-4 to 2.8×10-4 W·m-1 ·K-2 and the highest ZT value from 0.25 to 0.63. A proper co-doping results in a change in morphology from the amorphous-like structure represented by In2Se3 to the visible polycrystalline form, observed using HRTEM, and this change is directly related to the moderate enhancement of lattice thermal conductivity above 500 K.