
639Microwave Transistors
an electrical bias or other means, such as UV light, can be used. In oating-
gate devices, the programming can be done by either hot carrier injection
or a tunnelling process. The two cases are shown in Figures 14.48 and 14.49.
The hot electrons are ‘hot’ because they are heated to a high-energy state by
the high eld near the drain. Some of the hot electrons with energy higher
than the barrier height of SiO
2
/Si conduction band (~3.2 eV) can surmount
the barrier and get injected into oating gate.
Control gate Control gate
Floating
gate
Floating
dot
Substrate
Channel
Source
Source
Drain
Drain
FIGURE 14.48
Programming by hot carr