In this study, functional transparent conducting layers were investigated for Si-based photoelectric applications. Double transparent conductive oxide (TCO) films were deposited on a Si substrate in the sequence of indium tin oxide (ITO) followed by aluminum-doped zinc oxide (AZO). First, we observed that the conductivity and transparency of AZO dominate the overall performance of the double TCO layers. Secondly, the double layered TCO film (consisting of AZO/ITO) deposited by sputtering was compared to a AZO-only film in terms of their optical and electrical properties. We prepared three different AZO films: ITO:3min/AZO:10min, ITO:5min/AZO:7min, and ITO:7min/AZO:4min. The results show that the optical properties (transmittance, absorbance, and reflection) can be controlled by the film composition. This may provide a significant pathway for the manipulation of the optical and electrical properties of photoelectric devices.

A high-performing photoelectric device was realized for the MoS₂-embedded Si device. MoS₂-coating was performed by an available large-scale sputtering method. The MoS₂-layer coating on the p-Si spontaneously provides the rectifying current flow with a significant rectifying ratio of 617. Moreover, the highly optical transmittance of the MoS₂-layer provides over 80% transmittance for broad wavelengths. The MoS₂-embedded Si photodetector shows the sensitive photo-response for middle and long-wavelength photons due to the functional MoS₂-layer, which resolves the conventional limit of Si for long wavelength detection. The functional design of MoS₂-layer would provide a promising route for enhanced photoelectric devices, including photovoltaic cells and photodetectors.

NiO serves as a window layer for Si photoelectric devices. Due to the wide energy bandgap of NiO, high optical transparency (over 80%) was achieved and applied for Si photoelectric devices. Due to the high the high mobility, the heterojunction device (Al/n-Si/SiO2/p-NiO/ITO) provide ultimately fast photoresponses of rising time of 38.33 μs and falling time of 39.25 μs, respectively. This functional NiO layer would provide benefits for high-performing photoelectric devices, including photodetectors and solar cells.

Highly optical transparent photoelectric devices were realized by using a transparent metal-oxide semiconductor heterojunction of p-type NiO and n-type ZnO. A functional template of ITO nanowires (NWs) was applied to this transparent heterojunction device to enlarge the light-reactive surface. The ITO NWs/n-ZnO/p-NiO heterojunction device provided a significant high rectification ratio of 275 with a considerably low reverse saturation current of 0.2 nA. The optical transparency was about 80% for visible wavelengths, however showed an excellent blocking UV light. The nanostructured transparent heterojunction devices were applied for UV photodetectors to show ultra fast photoresponses with a rise time of 8.3 mS and a fall time of 20 ms, respectively. We suggest this transparent and super-performing UV responser can practically applied in transparent electronics and smart window applications.

A thin metal-embedding Schottky device was fabricated for an efficient photoelectric device. Semitransparent thick of 10 nm metal layers were deposited by sputtering of Ag and Ni on a Sisubstrate. The (111) N-type Si wafers with one-side polished, 450∼500 ㎛ and resistivity 1∼20 Ω·㎝were used. High rectifying ratio about 100 from Ni-Schottky device was achieved. This design wouldprovide an effective scheme for high-performing photoelectric devices.