Heterojunction between Al2O3 and SnO2 thin films for application in transparent FET

Abstract

Alternative materials for use in electronic devices have grown interest in the past recent years. In this paper, the heterojunction SnO 2 /Al 2 O 3 is tested concerning its use as a transparent insulating layer for use in FETs. The alumina layer is obtained by thermal annealing of metallic Al layer, deposited by resistive evaporation technique. Combination of undoped SnO 2 , deposited by sol-gel-dip-coating technique, and Al thermally annealed in O 2 -rich atmosphere, leads to fair insulation when the number of aluminum oxide layers is 4, with 0.3% of the current lost through the gate terminal as leakage current. This insulation is not obtained for devices with alumina layer treated for long time, under room atmosphere, due to degradation of the insulating film and interfusion with the conduction channel even using Sb-doped SnO 2 . The annealing of Al deposited on soda-lime glass substrate leads also to the formation of a Si layer, crystallized at Substrate/Al 2 O 3 interface. The conclusion is that for an efficient insulation the thermal annealing must be short and then, O 2 -rich atmospheres are preferred.

Effects of Solution History on Sol‐Gel Processed Tin‐Oxide Thin‐Film Transistors

“…Resistivity is ρ = 1.1 ± 0.2Ω·m in films spun from freshly prepared solution. However, it is significantly higher, ρ = 220 ± 40 Ω·m, when the aged solution is utilized: this is a relatively high value for doped SnO 2 . The transconductance of TFTs, measured at a drain voltage of 7 V while varying the gate voltage, is also different by about two orders of magnitude, (2.9 ± 0.6) × 10 −8 Ω −1 and (2.4 ± 0.3) × 10 −6 Ω −1 , for SbTO devices prepared from aged and fresh solutions, respectively.…”

“…However, it is significantly higher, q = 220 AE 40 ΩÁm, when the aged solution is utilized: this is a relatively high value for doped SnO 2 . 5,20,21,[25][26][27] The transconductance of TFTs, measured at a drain voltage of 7 V while varying the gate voltage, is also different by about two orders of magnitude, (2.9 AE 0.6) 9 10 À8 Ω À1 and (2.4 AE 0.3) 9 10 À6 Ω À1 , for SbTO devices prepared from aged and fresh solutions, respectively. Consequently, the differences in transconductance mirror the differences in resistivity and corroborate the importance of the "history" of the starting solution in the electrical properties of SbTO.…”

Interface conduction and photo-induced electrical transport in the heterojunction formed by GaAs and Ce3+-doped SnO2

“…CdTe/SnO 2 heterojunction has been proposed for solar cells devices [14] since the properties of CdTe, one of the best candidates for solar energy conversion, can be modulated by coupling with other materials. The combination of SnO 2 with Al 2 O 3 layer deposited by similar processes of the films deposition used in this paper, has led to a simple device with a potential combination for application as transparent transistors [15][16][17].…”

Annealing temperature influence on sol-gel processed zirconium oxide thin films for electronic applications

“…In order to find a substitute for the well-established silicon dioxide (SiO 2 ) in metal-oxide-semiconductor field-effect transistors (MOSFETs) [6], dielectric oxides with high dielectric constant (high-k) have been investigated, such as hafnia (HfO 2 ), alumina (Al 2 O 3 ), and zirconia (ZrO 2 ), because they are suitable to improve the channel modulation in MOSFETs through reduced tunneling current, even for small thicknesses [7][8][9]. Zirconia is a favorable alternative due to its high dielectric constant (k = 18-26), wide bandgap (4.7-7.8 eV), good thermal stability against silicate formation, excellent chemical inertness, high breakdown field, and good catalytic properties [2,3,10,11].…”