Effect of intentional chemical doping on crystallographic and electric properties of the pyrochlore Bi2Sn2O7

Tuning of hole carrier density in p-type α-SnWO4 by exploiting oxygen defects

“…However, this disadvantage is expected to be overcome via the selection of an appropriate crystal structure based on phase stability 18 . On the other hand, the hole carrier densities of Sn 2+ -based oxide semiconductors (10 17 -10 18 cm −3 ) are several orders of magnitude greater than those of Bi 3+ -based ones (10 13 -10 14 cm −3 ) [12][13][14][15][16][17] . Such characteristics of Sn 2+ -based oxide semiconductors in terms of carrier density are useful for designing electronic devices with high conductivities.…”

“…In this regard, precise tuning of the carrier densities of Sn 2+ -based p-type oxide semiconductors is highly necessary. However, intentional control over the hole carrier density remains a challenging undertaking 17,[19][20][21][22] . Especially, Sn 2+ -based oxides in the thin-film form still show the insulating properties [19][20][21][22] .…”

“…3,[9][10][11] Recently, several p-type oxide semiconductors with ns 2 orbitals have been developed based on predictions through theoretical approaches. [12][13][14][15][16][17] These state-of-the-art p-type oxide semiconductors can be categorized into two groups: one is for Sn 2+ -based oxide semiconductors, such as pyrochlore-type Sn 2 TM 2 O 7 (TM = Nb or Ta) 13 and layered-structure SnNb 2 O 6 and a-SnWO 4 ; 14,15 and the other is for Bi 3+ -based oxide semiconductors, such as perovskite-type BaBiO 3 , 16 double-perovskite-type Ba 2 BiTMO 6 , 12,16 and pyrochlore-type Bi 2 Sn 2 O 7 . 17 Of the two, Sn 2+ -based oxide semiconductors are less chemically stable than Bi 3+ -based ones because of their metastable Sn 2+ states.…”

“…[12][13][14][15][16][17] These state-of-the-art p-type oxide semiconductors can be categorized into two groups: one is for Sn 2+ -based oxide semiconductors, such as pyrochlore-type Sn 2 TM 2 O 7 (TM = Nb or Ta) 13 and layered-structure SnNb 2 O 6 and a-SnWO 4 ; 14,15 and the other is for Bi 3+ -based oxide semiconductors, such as perovskite-type BaBiO 3 , 16 double-perovskite-type Ba 2 BiTMO 6 , 12,16 and pyrochlore-type Bi 2 Sn 2 O 7 . 17 Of the two, Sn 2+ -based oxide semiconductors are less chemically stable than Bi 3+ -based ones because of their metastable Sn 2+ states. However, this disadvantage is expected to be overcome via the selection of an appropriate crystal structure based on phase stability.…”

“…However, intentional control over the hole carrier density remains a challenging undertaking. 17,[19][20][21][22] Especially, Sn 2+ -based oxides in the thin-film form still show the insulating properties. [19][20][21][22] This is likely because oxygen vacancies form spontaneously to compensate for the positive charge.…”