Photo-electrical Characterization of New CuAlNi/n-Si/Al Schottky Photodiode Fabricated by Coating Thin-Film Smart Material

Abstract

Micro/nano scale thin-film shape memory alloys (SMAs) have been used in many different miniaturized systems. Using them as thin-film metal components in fabrication of Schottky photodiodes has started a few years ago. In this work, a new SMA-photodiode device with CuAlNi/n-Si/Al structure was produced by coating nano-thick CuAlNi SMA film on n-Si wafer by thermal evaporation. The photoelectrical I-V, I-t and C-V photodiode characterization tests were carried out at room temperature under dark and different artifical light power intensities. It was observed that the new device exhibited photoconductive, photovoltaic and capacitive behaviors. By using the obtained data, the ideality factor (n) and barrier height (ϕb) were determined by conventional I-V method. The photodiode performance parameters of responsivity (Rph), photosensivity (%PS) and spesific detectivity (D*) were determined as good figure of merits. The current conduction mechanism analysis revealed that the space charge limited conduction (SCLC) mechanism is the dominant current conduction mechanism. By the drawn reverse squared C-2-V plots, the values of donor concentration (ND), diffusion potential (Vd), Fermi level (EF) and also barrier height (ϕb) were determined for the SMA-photodiode. The results indicated that the new SMA-photodiode device can be useful in optoelectronic communication systems and photosensing applications.