Reliability Studies on High-Temperature Operation of Mixed As/Sb Staggered Gap Tunnel FET Material and Devices

The reliability of structural and electrical properties of mixed As/Sb staggered gap tunnel field-effect transistors (TFETs) for high-temperature operation was comprehensively investigated from 25 ^°C to 150 ^°C. Temperature-dependent X-ray measurements showed identical strain relaxation of the active region, indicating that no additional dislocations were introduced at 150 ^°C. Symmetric 2-D surface crosshatch patterns before and after annealing suggested no significant structural properties change during high-temperature operation. No extra interdiffusion of species at the source/channel heterointerface was observed at 150 ^°C, confirmed by secondary ion mass spectrometry measurement. The leakage current of the fabricated reverse-biased p⁺-i-n⁺ diode exponentially increased with increasing temperature due to Shockley-Read-Hall generation-recombination mechanism. The on-state drain current of the TFET device showed weak temperature dependence, and it decreased with increasing temperature from 25 ^°C to 100 ^°C due to the variation of Fermi distribution and the increase in channel resistance but increased from 100 ^°C to 150 ^°C due to the reduction of both band-gap energy and the effective tunneling barrier height. The subthreshold slope has a strong positive temperature-dependent property particularly at higher temperature due to trap-assisted tunneling process. These experimental results demonstrated stable structural properties and distinguished device characteristics of the mixed As/Sb staggered gap TFETs at higher operating temperature. The temperature-dependent structural and device properties of the mixed As/Sb staggered gap TFET highlight the importance of the reliability on high-temperature operation of TFETs for future low-power digital logic applications.