On resistive switching and dielectric spectroscopy characteristics of topological insulator-based heterojunction for memory applications

Herein, bismuth telluride (Bi₂Te₃) thin films thermally grown under vacuum have been integrated with p-Si in a heterojunction configuration of Au/Bi₂Te₃/p-Si/Al for resistive switching random-access memory (RRAM) applications. The quality of the grown films was evaluated in terms of crystal structure and films’ morphology using XRD and FE-SEM techniques, respectively. The dark I-V under sweeping cycles between ± 5 Volts revealed the bidirectional RRAM features. The heterojunction parameters are extracted using Thermionic emission and Cheung-Cheung models. The conduction mechanism under forward/reverse biasing is discussed, emphasizing the impact of the interfacial states profile on the junction performance. Furthermore, the AC spectroscopical features of the designed heterojunction have been tested under different modulating frequencies, declaring a nontrivial capacitance behavior (i.e., negative capacitance). Based on the recorded (C-V) data at different frequencies, the built-in potential, V_bi, depletion region width, W_d, acceptor doping concertation, N_A, and barrier height, Φ_B, are evaluated. The extracted V_bi, W_d, N_A, and Φ_B magnitudes at 1 MHz were about 0.6 Volt, 1.06 μm, 7.16 × 10²⁶ cm⁻³, and 1.095 eV, respectively. Ultimately, the Re [Z]-Im [Z] plot showed an interesting switching plot behavior with notable promising negative capacitance features. This astonishing performance of the fabricated heterojunction suggests this design for memristor applicability. An exciting [Re [Z]-Im [Z]] relation plot that may be useful in fabricating electrical switching electronic devices by using the frequency of the applied AC signal as a probe controlling factor (10 kHz to 7 MHz).