Using a lamp as a heat source?

So instead of using a heat mat would using a lamp and dome be effective?

it will produce heat but not enough to heat the soil to the right temps. Buy a heat mat.

First time ever germinating pepper I germinated bhuts that way, using a regular 50W Incandescent light bulb in a mini greenhouse I made, they seeds germinated great even tho it was the middle of the winter.

I used a slow cooker .....

My sprouting / early growth enclosure uses 8 x CFL bulbs as the heat source. All sides are covered and the soil reaches roughly 85F for 16 hours then room temperature at night for 8 hours... I am lazy and just kept the same schedule as after the sprouts come up instead of leaving the lights on 24hours/day till they do, but to keep the soil at 85F the air is a bit warmer so at the point of sprouting I let a little air into the enclosure and put the earlier sprouts near that so they stay cooler while the back with no sprouts yet stays warmer.

If you're going to add heat you really need a thermometer to be sure you're not cooking them.