Electrical switching device and method of embedding catalytic material in a diamond substrate

An electrical device comprising:

• a substrate including at least one diamond layer;
• at least one first electrode in contact with said substrate, wherein at least one said first electrode includes at least one electrically conductive protrusion extending into said substrate;
• and
• at least one second electrode in contact with said substrate and spaced from the or each said first electrode wherein said substrate comprises, adjacent at least a distal end of at least one said protrusion, a diamond material including first impurities adapted to modify the electrical characteristics of said diamond material adjacent said distal end.