533Microwave Diodes
13.5.2.1 Properties of High Field Domain
It is to be noted that the high eld domain follows certain set norms in its
formation and extinction. These norms referred to as properties of high eld
domain are as below.
1. A domain starts to form near the cathode whenever in the region
of a sample the applied E-eld exceeds threshold value (i.e., E > E
th
).
This domain drifts with carrier stream through the device towards
anode. When the increase of E results in decrease of drift velocity
(
υ
d
) the (GaAs) sample exhibits negative resistance.
2. If a sample (or device) already contains domains then any addition-
ally applied E-eld results in increase of the domain size due to
absorption of more energy from the eld. ...