Effects of chalcogen substitution on electronic properties and chemical bondings of delafossite CuAlO₂

Abstract

Due to its p-type conductivity, CuAlO 2 has been widely studied. However, the conductivity of p-type CuAlO 2 is much lower than that of n-type, which limits its applications. We used the generalized gradient approximation and hybrid functional B3LYP to study the effects of chalcogen substitution on the electronic properties and chemical bondings of delafossite CuAlO 2 . The calculated results show that the doping of chalcogen (S, Se, and Te) substituting for O is thermodynami-cally stable. The calculated volumes, bandgaps, and valenceband widths of dopants have been detailedly discussed, indicating that the volumes and valence-band widths are increased, but the bandgaps are decreased. The density of states and charge-density distribution ranges have been analyzed, suggesting that chalcogen substitution is a good way to design new p-type Cu-based TCOs.

Effects of different concentration S-doping on the structural stability and electronic structures of delafossite CuAlO2

“…The results indicated the S doping could enhance the conductivity of CuAlO 2 . The similar conclusions of increased carrier mobility and conductivity have been shown after chalcogen doping at O site [16,18,19]. Then, we want to know how the doping concentration influences the p-type conductivity of CuAlO 2 .…”

Electronic and Dielectric Properties of MoV-Oxide (M1 Phase) under Alkane Oxidation Conditions

“…Besides the application of tellurium compounds in heterogeneous catalysis, tellurides are frequently used in electronic applications (e.g., solar cells, thermoelectric materials, and optical storage media). , There are reports of n-type semiconducting mixed-metal tellurium oxides and of Te-doped n-type In 2 O 3 , which leads to an altered conduction band structure but with a poor doping effectiveness . Tellurium doping was also applied to enhance the p-type conductivity of other metal oxides when substituting oxygen, e.g., in CuAlO 2 , where it leads to a decrease of the band gap and increased covalency. , Recently, it has been proposed that the reduction and subsequent emission of tellurium from the hexagonal channels in the M1 structure in the course of the oxidation reaction create reactive O – species, which are involved in the alkane activation (similar to vanadyl species V 5+ = O → V 4+ –O – ) . Importantly, the authors indicated that the removal of Te might ultimately change the semiconducting properties from n-type (with Te) to p-type (without Te) based on density functional theory (DFT) calculations .…”

“…103 Tellurium doping was also applied to enhance the p-type conductivity 104 of other metal oxides when substituting oxygen, e.g., in CuAlO 2 , where it leads to a decrease of the band gap and increased covalency. 105,106 Recently, it has been proposed that the reduction and subsequent emission of tellurium from the hexagonal channels in the M1 structure in the course of the oxidation reaction create reactive O − species, which are involved in the alkane activation (similar to vanadyl species V 5+ = O → V 4+ −O − ). 107 Importantly, the authors indicated that the removal of Te might ultimately change the semiconducting properties from n-type (with Te) to p-type (without Te) based on density functional theory (DFT) calculations.…”

Electronic and magnetic properties of second main-group and second sub-group metals substitution for Al in delafossite CuAlO2

“…The covalent nature of Cu O bonds is increased according to the charge density (LDA calculation): the charge of Cu in pure CuAlO 2 is 0.28e, and the charges of Cu near the doped atoms are 0.15e, 0.11e, 0.16e, 0.17e for Be Mg Ca Sr, respectively, which is good for hole delocalization. In a word, the effect of II-group metals substitution for Al in delafossite CuAlO 2 is the same as the chalcogen substitution for O [35], which all enhance p-type conductivity. Moreover, experiments reported that the excess oxygen atoms induced the increase of p-type conductivity [36], so the relation between oxygen stoichiometry and generated holes by bivalent cations substitutions seems interesting, which should be solved by designing a special model.…”