An electrical device like this requires a reverse leakage current of 200nA @ 15V.While the device is operating, the maximum voltage - Zener (Nom) is reduced to 20.22V.
MTZJ20SD R0G Features
reverse leakage current of 200nA @ 15V 200nA @ 15V is the maximum voltage (Tol)
MTZJ20SD R0G Applications
There are a lot of Taiwan Semiconductor Corporation MTZJ20SD R0G applications of zener single diodes.