How does the multiple constituent affect the carrier generation and charge transport in multicomponent TCOs of In–Zn–Sn oxide

Abstract

The main purpose of this work is to make clear that in the newly synthesized multicomponent materials IZTO, namely, Sn/Zn cosubstituted In 2 O 3 , how can these cosubstituted dopants interact with each other and affect the electronic properties. We carry out a series of systematic Density Functional Theory calculations. Compared with ITO materials, the existence of Zn 2+ in IZTO is important for the control of the electronic properties. Although there is large lattice distortion in the local structure around Zn 2+ due to the Jahn-Teller effect, it releases distortions induced by other defects and thus reduces the formation energy of cosubstitution of the Zn/Sn impurity pair in In 2 O 3 . The V O defect prefers to form in the ZnO 6 octahedron for the breaking of the Zn-O bond is easier than the Sn-O bond, which generates free electrons. In all IZTO configurations with and without defects, the bottom of conduction bands is comprised mainly of cation-s and O-p orbitals, which constructs a three dimensional network for charge transport. The bandstructure renormalization effect exerted by Zn atoms narrows the band gap. The existence of Zn atoms, on the one hand, weakens the spatial localization and orbital localization effects induced by defects and on the other hand strengthens the charge transport ability. These results indicate that the multicomponent semiconductor IZTO is an excellent candidate for the low indium content TCOs. Our work is useful to control the physical properties of IZTO experimentally, and is also helpful in understanding other multicomponent TCO materials.

Site Identity and Importance in Cosubstituted Bixbyite In2O3

“…These findings corroborate earlier reports of the stability of Zn on the d-site and Sn on the b-site. In the prior study, however, substitution on solely the b-or d-site was not mentioned [12]. This also fits with what is currently known experimentally, as Sn prefers the b-site in ITO and M 2+ is always present on the d-site in M x In 2-2x Sn x O 3 .…”

“…The solubility limits of cosubstituted bixbyite, however, can occupy up to 50% of the cation sites and therefore must alter the d-site either exclusively or in combination with the b-site. The impact of multiple constituents (i.e., only Sn vs. M/Sn pairs) on the electronic properties has already drawn investigative interest, particularly for M = Zn, but the importance of site occupancy has not yet been tied to either the multiple constituents or the electronic properties [11,12]. The constituent identities and their site preferences have been linked to crystal structure, however, as exhibited by the cosubstitution of Zn/Ge pairs.…”

Influence of Sputtering Power on the Electrical Properties of In-Sn-Zn Oxide Thin Films Deposited by High Power Impulse Magnetron Sputtering

“…As the sputtering power reaches 400 W, the higher sputtering power is conducive to the ionization of the working gas Ar [14,37,38], which could transfer sufficient energy to the sputtering species (In, Sn, and Zn atoms or clusters) and improve their activity. This causes Zn In , Sn In , and V O to form easily, enhancing the carrier concentration (Zn In lowering the formation energy of Sn In and V O , while Sn In and V O are the donor defects in ITZO films).…”

“…the substitution of In 3+ by Zn 2+ ) is beneficial in forming V O (oxygen vacancies), and Sn In (i.e. the substitution of In 3+ by Sn 4+ ) donor defects, which improve the carrier concentration [14,15].…”

Tuning the physical properties of amorphous In-Zn-Sn-O thin films using combinatorial sputtering

“…In this case, Sn acts as an electron trap rather than an electron donor in IZTO, with the formation of donor acceptor pairs from Zn 2+ and Sn 4+ , which would prevent carrier generation. [25] In fact, as reported by Lu et al [26] the solubility of Zn/Sn dopants are both promoted in IZTO more than Sn In or Zn In defects in In 2 O 3 because of the isovalent substitution of Sn 4+ and Zn 2+ for two In 3+ . The existence of Zn In is beneficial to the donor defects favorable to the increase of carrier concentration in IZTO.…”