La_2/3Sr_1/3VO₃ Thin Films: A New p‐Type Transparent Conducting Oxide with Very High Figure of Merit

Abstract

is directly related to its carrier concentration (n) and carrier mobility (μ) by σ = neμ where e is the elemental charge. The carrier mobility is given by / µ τ = * e m with τ being the carrier relaxation time and m* the carrier effective mass. [5] The optical transparency (T opt ) is exponentially proportional to both optical absorption coefficient (α) and film thickness (d), via T opt ∝ e -αd . [6] The T opt of a thin film can be optimized by choosing the material with weak absorption or decreasing the film thickness. Accordingly, the strong optical absorption due to the direct interband transition usually characterizes the optical bandgap.A typical approach to TCOs is starting from wide bandgap oxides (e.g., In 2 O 3 , SnO 2 , and ZnO) and making them conducting by doping, which is successful in developing a series of high-performance n-type TCOs such as Sn-doped In 2 O 3 (ITO), Al-doped ZnO (AZO), and F-doped SnO 2 (FTO). [7][8][9][10] The conduction band minimum (CBM) and valence band maximum (VBM) of these parent oxides are primarily consisted of the unoccupied ns 0 orbital and fully occupied oxygen 2p orbital, respectively. The highly dispersive CBM of ns orbital gives small (high) m* (μ) and excellent n-type conductivity by donor doping. [1,9] However, a straightforward transformation of the n-type TCOs to p-type TCOs via acceptor doping is very difficult. The localized oxygen 2p orbital at the VBM leads to large (low) hole m* (μ), which becomes the fundamental limitation to obtain highly mobile holes at the VBM. Furthermore, it is difficult to introduce hole carriers due to the high formation energy of the native acceptors as well as the self-compensation effect (easily formed native donors annihilate holes). [11,12] Engineering the VBM by alloying the oxygen 2p orbitals with the d or s orbitals of metal cations, i.e., "chemical modulation of the valence band" (CMVB) proposed by Kawazoe et al., has been used to solve this conundrum and promoted the development of a number of p-type TCOs. [13][14][15][16][17][18][19][20][21][22][23] High-throughput material screening has also identified several highly promising p-type TCOs displaying small (high) hole m* (μ). [24][25][26] Despite the improvement of hole mobility, these p-type TCOs still exhibit low σ, several orders of magnitude lower than that of n-type TCOs, primarily due to the doping bottleneck in increasing the hole concentration by intrinsic defects (cation vacancies or interstitial oxygen) and/or the solubility limit of the acceptors. Transparent conducting oxides (TCOs) are a unique series of materials combining electrical conductivity with optical transparency. Most of the commercially available TCOs are of the n-type. The performance of p-type TCOs, however, is far behind their n-type TCO counterparts primarily due to the doping bottleneck and low hole mobility. Herein, a Mott-Hubbard insulator of LaVO 3 is proposed as the starting point for exploring p-type TCOs. Substitution of La 3+ by Sr 2+ can introduce high hole carrier concentration at th...

Metal oxide nanoparticles and their applications in nanotechnology

“…These p-type TCOs films made of La 2/3 Sr 1/3 VO 3 demonstrated weak absorption in the visible region, the highest transmission between 53.9 and 70.1% in the visible region, modest carrier mobility, and the highest conductivity in the range 742.3-872.3 S cm −1 at RT. Therefore, the good balance between optical transparency and electrical conductivity in the delafossite compound led to these high figures of merit as compared with other developed p-type TCOs [224]. It follows that p-TCO thin films deposited by codoping could propose better optical, electrical properties combined with maximum conductivity without interfering with their visible transmittance.…”

Interfacial Octahedral Manipulation Imparts Hysteresis‐Free Metal to Insulator Transition in Ultrathin Nickelate Heterostructure

“…The crystal truncation rods exhibit the same Q x / Q y values as the Bragg peaks, demonstrating that the NNO films are fully coherently strained to the substrate . The horizontal black and orange lines are referenced to the peak positions by simulations for the substrate and film, respectively . Note that the L ‐values for 013 pc and pc are same, while the L ‐values for pc and 103 pc differ, suggesting monoclinic symmetry and a single domain variant for both the NGO substrate and NNO film.…”

“…b) Intensity as a function of L across the 002 pc for the 3 and 6 nm NNO thin films at 300 K. The dash lines are simulated diffraction intensity of films by referring ref. . The black stars indicate the NNO peak positions.…”

p-type transparent superconductivity in a layered oxide

“…In contrast to a traditional concept (taking ITO as an example, high-mobility semiconductor In 2 O 3 is doped with a small amount of Sn), they shed light on correlated metals, where large number of carriers resides in low-mobility TMOs. On the basis of this strategy, perovskite-type AMO 3 (A = Ca, Sr, and La; M = V, Mo, and Cr) have been found to be good TCs, both n-and p-type (5)(6)(7)(8). However, the studies have been so far limited to the perovskite-type TMOs.…”