Gate leakage current for a JFET?
JFETs have a junction and an associated Is &quot;leakage&quot; current. However it's often pretty small and one can use a JFET as a low leakage diode. For example, J201 has 100pA maximum leakage vs. several nA for a 1N4148 typically and 25nA guaranteed (all numbers here are at 25°C).
The \$\text{SiO}_2\$ oxide gate insulation in a typical MOSFET has very low leakage typically, though datasheets often do not guarantee anything like the typical. Win Hill has measured typical gate leakage currents in the &quot;few fA&quot; for the 2N7000, for example, even though the guaranteed number is 100nA.