Interface properties of atomic layer deposited TiO2/Al2O3 films on In(0.53)Ga(0.47)As/InP substrates

Tunable Color Coating of E-Textiles by Atomic Layer Deposition of Multilayer TiO2/Al2O3 Films

We successfully fabricated a conductive E-textile and color-coated E-textile by depositing multilayer Al₂O₃/TiO₂ on a conductive E-textile through atomic layer deposition (ALD). Pt was deposited on an E-textile as a conductive layer via low-temperature ALD. The color of the coated conductive E-textile could be tuned to violet, green, or pink by simply varying the thickness of the Al₂O₃ and TiO₂ layers. Both experimental and simulation results revealed that seven different colors can be obtained with single-layer TiO₂ and multilayer Al₂O₃/TiO₂, depending on the film thickness and their refractive indices. This method is highly effective for enhancing the fastness of structural color on conductive E-textiles. Furthermore, the mechanical properties and chemical stability of the color-coated E-textiles were investigated. The color-coated E-textiles could withstand acidic and basic solutions, with almost negligible changes in their morphology; this in turn indicates their excellent chemical stability. These switchable stable color-based conductive E-textiles can be used as a platform to directly integrate future wearable electronics in textiles.

Improved performance of AlGaInP red micro-light-emitting diodes with sidewall treatments

The electrical and optical improvements of AlGaInP micro-light-emitting diodes (µLEDs) using atomic-layer deposition (ALD) sidewall passivation were demonstrated. Due to the high surface recombination velocity and minority carrier diffusion length of the AlGaInP material system, devices without sidewall passivation suffered from high leakage and severe drop in external quantum efficiency (EQE). By employing ALD sidewall treatments, the 20×20 µm² µLEDs resulted in greater light output power, size-independent leakage current density, and lower ideality factor. The forward current-voltage characteristic was enhanced by using surface pretreatment. Furthermore, ALD sidewall treatments recovered the EQE of the 20×20 µm² devices more than 150%. This indicated that AlGaInP µLEDs with ALD sidewall treatments can be used as the red emitter for full-color µLED display applications.

Capacitance-voltage characteristics of sub-nanometric Al2O3 / TiO2 laminates: dielectric and interface charge densities

Advanced amorphous sub-nanometric laminates based on TiO₂ and Al₂O₃ were deposited by atomic layer deposition at low temperature. Low densities of 'slow' and 'fast' interface states are achieved with values of 3.96 · 10¹⁰ cm^-2 and 4.85 · 10^-9 eV^-1 cm^-2, respectively, by using a 40 nm laminate constituted of 0.7 nm TiO₂ and 0.8 nm Al₂O₃. The sub-nanometric laminate shows a low hysteresis width of 20 mV due to the low oxide charge density of about 3.72 · 10¹¹ cm^-2. Interestingly, such properties are required for stable and reliable performance of MOS capacitors and transistor operation. Thus, decreasing the individual layer thickness to the sub-nanometric range and combining two dielectric materials with oppositely charged defects may play a major role in the electrical response, highly promising for the application in future micro and nano-electronics applications.

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application

Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry.

Reduced recombination with an optimized barrier layer on TiO2 in PbS/CdS core shell quantum dot sensitized solar cells

A solar cell based on a double coating electrode (MgO/Al₂O₃) on TiO₂ yielded excellent performance with an efficiency (η) of 3.25%.