Interface Trap-Induced Variability and Thermal Reliability in Epitaxial Layer Heterojunction Vertical Tunnel FET

Abstract

Abstract This study presents an Epitaxial Layer Heterojunction Vertical Tunnel Field Effect Transistor (EL‑HJ-VTFET) employing Mg2Si as the source and a SiGe epitaxial layer to enhance band-to-band tunneling (BTBT) and overall device efficiency. The narrow bandgap of Mg2Si (0.6–0.7 eV) enables effective carrier injection, while the SiGe layer improves band alignment, reduces tunneling width, strengthens the electric field, and mitigates lattice mismatch defects, thereby increasing device reliability. The impact of interface trap charge (ITC) density (±1010 to ± 1012 cm–2) and temperature (250–400 K) is analyzed to analyze the reliability. Positive interface charge yields a high current ratio (ION/IOFF ≈ 2.10 × 109) but increases threshold voltage and degrades subthreshold swing. In contrast, negative interface charge achieves a steep subthreshold swing (~23.18 mV/dec), lower threshold voltage, and reduced leakage, albeit with a lower current ratio (~2.15 × 107). Benchmarking has been carried out with reported experimental devices in terms of electrical metrics. Therefore, the device shows strong potential for ultra-low-power VLSI and biosensing applications.