An insight to the performance of vertical super-thin body (VSTB) FET in presence of interface traps and corresponding noise and RF characteristics

Abstract

We investigated vertical super-thin body (VSTB) FET performance in presence of different interface (HfO2/Si) trap distributions (uniform and Gaussian) and concentrations using TCAD tools. For trap concentration (TC) of 1013\xa0eV−1\xa0cm−2, the percentage change in on-to-off current ratio (Ion/Ioff) is 93.91% for uniform trap (UT) and 49.8% for Gaussian trap (GT) distribution. For the same TC, subthreshold swing (SS) shows percentage change of 5.1% for UT and 11.41% for GT distribution. Thus, the device performance shows good immunity for TC up to 1013\xa0eV−1\xa0cm−2. However, for TC\u2009=\u20091014\xa0eV−1\xa0cm−2 SS degrades significantly. The influence of traps on the cumulative effect of three noise sources (diffusion\u2009+\u2009generation–recombination/G–R\u2009+\u2009flicker) and on individual noise sources (G–R and diffusion) is explained qualitatively at low and high frequencies (f\u2009=\u20091\xa0MHz and 10\xa0GHz). The study shows that the overall noise cannot disturb the device performance at very high frequency. Various radio-frequency (RF) parameters like transconductance (gm), total input capacitance (Cgg), gate-drain capacitance (Cgd), unit-gain cutoff frequency (fT), and gain–bandwidth-product (GBP) are also studied for variation of trap types. For TC\u2009=\u20091014\xa0eV−1\xa0cm−2, the percentage change in fTmax (GBPmax) is −\u200921.43% (−\u20098%) for UT and −\u200922.86% (−\u20099.6%) for GT distribution.