Fabrication and Operating Mechanism of Deep‐UV Transparent Semiconducting SrSnO₃‐Based Thin Film Transistor

Abstract

Thin film transistor (TFT) with deep-UV transparency is a promising component for the next generation optoelectronics such as biosensor. Among several deep-UV transparent oxide semiconductors, SrSnO3 is an excellent candidate material owing to its wide bandgap (~4.6 eV) and rather high carrier electron mobility. Here we show fabrication and operation mechanism of the SrSnO3-TFT. We fabricated metal-insulatorsemiconductor structure on the 28-nm-thick SrSnO3 film. The resultant TFT showed clear transistor characteristics; the on-to-off current ratio was ~10 2 , the threshold voltage was ~ −18 V, and the field effect mobility was ~14 cm 2 V −1 s −1 . The effective thickness of the electron channel gradually increased with gate voltage and saturated at ~5 nm, which was evaluated by the thermopower modulation. The present results would be helpful for utilizing deep-UV transparent TFTs for biosensing applications.

Fully Deep‐UV Transparent Thin Film Transistors Based on SrSnO3

“…While the field effect mobility was relatively modest, at ≈9 cm 2 V −1 s −1 , the accumulation-mode TFT demonstrates a smaller subthreshold swing of 0.23 V dec −1 (Figure S4d, Supporting Information). Compared with the SrSnO 3 -based TFT that Mian Wei previously reported, [26] our device exhibited a higher μ FE value and a higher on-off ratio (I ON /I OFF ). Considering that Mian Wei previously reported thin films of La-doped SrSnO 3 with high Hall mobility exceeding 40 cm 2 V −1 s −1 , [14] this enhanced performance of our device should be attributed to the fabrication process of the device rather than the quality of the active layer.…”

“…This incorporation makes the entire device transparent in the DUV region, further distinguishing our TFT from other reported ones (Table S1, Supporting Information). [26][27][28][29][30][31][32][33][34][35]…”

Significant Suppression of Cracks in Freestanding Perovskite Oxide Flexible Sheets Using a Capping Oxide Layer

“…The optical bandgap was 4.4 eV, which is slightly smaller than that observed for Ta-doped SrSnO 3 , Nb-doped SrSnO 3 , and LSSO films on MgO substrates (∼4.6 eV). ,− Figure b shows the electrical conductivity (σ) of the LSSO sheet as a function of temperature ( T ). The value of σ increases with decreasing T , indicating that the LSSO sheet is a degenerate semiconductor, similar to LSSO films. − The σ of the sheet was 1.6 × 10 3 S/cm at room temperature, which is slightly lower than that of the LSSO film on the STO substrate (3 × 10 3 S/cm) but similar to that of a-ITO (2 × 10 3 S/cm) …”

Tuning of the Optoelectronic Properties for Transparent Oxide Semiconductor ASnO3 by Modulating the Size of A-Ions

“…14,15 When a smaller Sr atom is substituted in the A-site, SrSnO 3 shows a E g of ∼4.6 eV, allowing SrSnO 3 -based TFT to transmit DUV light with a wavelength of 260 nm by more than 50%, which exhibits great potential in DNA sensing in biology. 16,17 ASnO 3 has a perovskite structure composed of corner-sharing SnO 6 octahedra. The crystal structure of ASnO 3 is closely related to the lattice parameter, which is determined by A-site substitution.…”

“…Recently, La-doped ASnO 3 (A = Ba, Sr, and Ca) films have attracted rising attention as the active TOS channel, owing to their wide band gap and high electrical conductivity. La-doped BaSnO 3 (LBSO, E g ∼ 3.1 eV) thin films show high mobility values of 115–183 cm 2 V –1 s –1 at room temperature. , When a smaller Sr atom is substituted in the A-site, SrSnO 3 shows a E g of ∼4.6 eV, allowing SrSnO 3 -based TFT to transmit DUV light with a wavelength of 260 nm by more than 50%, which exhibits great potential in DNA sensing in biology. , ASnO 3 has a perovskite structure composed of corner-sharing SnO 6 octahedra. The crystal structure of ASnO 3 is closely related to the lattice parameter, which is determined by A-site substitution.…”