If you look at the data sheet of a MOSFET ( for example; IPD50N03S2-07 ), you see the Drain current versus Drain-Source Voltage chart, commonly known as "Safe Operating Area."

From this safe operating area chart, can we easily say that the first boundary on the left is during the Linear Mode Operation of MOSFET, and then Saturation Mode and then the area to the right of the right-most boundary as the avalanche mode?

Or in other words, my question is whether we can tell from the safe operating area chart, which region is linear mode, which is saturation mode and which is avalanche mode?

 

The line with positive gradient on the left is the limit imposed by Rds(on). The right vertical line is the maximum VDS. The horizontal line on the top is the maximum ID (usually limited by bonding wire). The negative gradient lines are the maximum power dissipation (thermal limit) at different ID pulse width.