p-type conductivity in wide-band-gap BaCuQF (Q=S,Se)

Abstract

BaCuQF (Q=S,Se) materials, candidate transparent p-type conductors, were prepared by solid-state reaction, and their bulk electrical and optical properties were evaluated. The room-temperature Seebeck coefficient and electrical conductivity of undoped BaCuQF pellets were +56 μV/K and 0.088 S/cm, respectively, for the sulfide fluoride, and +32 μV/K and 0.061 S/cm, respectively, for the selenide fluoride. The conductivity was greatly enhanced by the substitution of several percent of K for Ba; the highest conductivities were 82 S/cm for Ba0.9K0.1CuSF and 43 S/cm for Ba0.9K0.1SeF. The band gaps for Q=S and Q=Se were measured to be 3.2 and 3.0 eV, respectively. Undoped BaCuSF exhibits strong red luminescence near 630 nm under ultraviolet excitation.

P‐Type Transparent Cu‐Alloyed ZnS Deposited at Room Temperature

“…In films x = 0.09, 0.21, and 0.30, the conductivity decreases only very slightly below room temperature and essentially plateaus at a constant value, suggesting degenerate hole conduction within the valence band. This behavior is similar to metallic conduction in other p-type transparent sulfides, such as doped CuAlS 2 , [33,34,49,50] but contrasts with the activated transport mechanisms typical in oxide-based TCMs (c.f. Table S1).…”

“…Interestingly, it was found in some cases that the incorporation of S as a second anion could function to delocalize the VBM, leading to predictions of lower VBM effective masses and, potentially, higher hole mobility. Indeed, there are a few literature reports of relatively good p-TCM performance achieved using non-oxide chalcogenide-based p-TCMs such as CuAlS 2 and BaCu 2 (S, Se)F. [33][34][35] 5…”

Transparent Electrodes for Efficient Optoelectronics

“…[59,78] This approach has been demonstrated experimentally with Cu-based p-type transparent chalcogenides (S, Se, Te) and oxychalcogenides, most notably CuAlS 2 , BaCu 2 S 2 , BaCu 2 (S, Se)F, and Cu-Zn-S, resolving one of the issues with the localized O 2p orbital and, upon optimization, reaching conductivities greater than 10 S cm −1 . [79][80][81][82] The Cu-Zn-S system (also notated Cu y S:Cu x Zn 1-x S) includes films grown at temperatures lower than 100°C by pulsed laser deposition (PLD) and chemical bath deposition (CBD), achieving p-type conductivities approaching those of the n-type TCOs ( Figure 1). [82] Additionally, Hosono and co-workers have …”

Novel Materials Development for Polycrystalline Thin-Film Solar Cells: Final Subcontract Report, 26 July 2004--15 June 2008

“…Relatively few wide-bandgap, p-type semiconductors appropriate for use as p-type thinfilm window layers are known to exist [25], [26], [27], [28], [29], [31], [32], [33], [34], [35]. Table 2 is a list of wide-bandgap p-type material candidates.…”

“…BCTF was initially develope d as a transparent p-type conductive material [26], [27], [28], [29], [3 1]. With a bandgap of 2.3 eV (indirect) and 3.0 eV (direct), a carrier concentration of ~ 10 20 cm −3 , a mobility as large as 8 cm 2 /V⋅ s, and 70-80 % transparency in the visible portion of the electromagnetic spectrum, [29], [31 BCTF is potentially useful as a p-type insertion layer ] for the realization of a pin double-heterojunction thin-film solar cell.…”