Reevaluating the Hartman effect for field emission

An electron wave packet tunneling through a barrier has transmission (or ``group delay'') time ${\ensuremath{\tau}}_{g}$ that, for rectangular barrier, is commonly held to become independent of the width $L$ as increases (the McColl-Hartman effect). In present study, it shown that first, effect dependent upon Gamow factor $\ensuremath{\theta}(k)$ vanishes, and only when large; second, triangular model field emission, although can be large small field, vanishes energy matches height.