Influence of the gate leakage current on the stability of organic   single-crystal field-effect transistors
  We investigate the effect of a small leakage current through the gate insulator on the stability of organic single-crystal field-effect transistors (FETs). We find that, irrespective of the specific organic molecule and dielectric used, leakage current flowing through the gate insulator results in an irreversible degradation of the single-crystal FET performance. This degradation occurs even when the leakage current is several orders of magnitude smaller than the source-drain current. The experimental data indicate that a stable operation requires the leakage current to be smaller than $10^{-9} \ \mathrm{A/cm}^2$. Our results also suggest that gate leakage currents may determine the lifetime of thin-film transistors used in applications. 
R. W. I. de Boer, N. N. Iosad, A. F. Stassen, T. M. Klapwijk, and A.   F. Morpurgo