共掺杂Cu,Te后禁带宽度变窄对In2Se3基半导体热电性能的影响

Effect of Band Gap Reduction on the Thermoelectric Properties of In2Se3 Based Semiconductors after Co-Doping of Cu and Te

摘要:

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1.32 eV减小到1.14 eV。掺杂后电学性能得到了大幅度的改善。最大功率因子由0.76′10-4增大到2.8′10-4 W·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500 K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

Abstract:

a-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 a-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