High electron mobility transistor with GaN/Al.sub.x Ga.sub.1-x N heterojunctions

A transistor, comprising:

• (a) a substrate;
• (b) a buffer, the buffer being deposited on the substrate;
• (c) a first active layer, the first active layer being composed essentially of GaN, the first active layer being deposited on the buffer;
• (d) a second active layer, the second active layer being composed essentially of Al.sub.x Ga.sub.1-x N, where x is greater than 0 and less than 1;
• and
• (e) a plurality of electrical connections, the electrical connections residing on the second active layer, the plurality of electrical connections comprising:
• (i) a source connection, the source connection residing on the second active region;
• (ii) a gate connection, the gate connection residing on the second active region;
• (iii) a drain connection, the drain connection residing on the second active region;
• thereby permitting a difference of electrical potential to be applied to the second active region so as to permit operation as a transistor.