Effect of Different Metallic Contacts on the Device Performance of a p-n Heterostructure of a Topological Insulator and Silicon (p-Bi2Te3/n-Si)

Abstract

This article investigates the performance of the p-Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /n-Si heterostructure diode with different metallic contacts. The heterostructure was realized by the thermal coating of a topological insulator (TI) Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> film on n-Si. The crystal phase study of the Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> film was done by X-ray diffraction (XRD), while the microstructural and morphological study was done by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The CV characterization for the diode showed almost no hysteresis except for the gold (Au) contact device, which could be due to the trapping of electrons at the interface. The current-voltage (IV) measurement was done in the dark, which confirmed the formation of p-n diode heterostructure. Diode having platinum (Pt) metallic contact exhibited the best ideality factor (n = 7.00), while the diode with gold (Au) contact closely followed it (n = 8.91). The best figure of merit (FOM) ≈ 2.588 was observed for Pt contact device with the maximum rectification ratio (RR) ≈ 442 and majority charge carrier concentration (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A</sub> ) = 1.47 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">25</sup> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The experimental results of I - V for different contact devices were further simulated using the two-diode model and various diode parameters were extracted. The current density- voltage (JV) and local ideality factor-voltage (nV) plots were studied to find the ideality factor and recombination current (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> ) for different metallic contact devices. The Pt contact diode was found to be nearest to the ideal behavior of a diode exhibiting the least recombination current (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> ) = 9.7 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-17</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .