Image Number 4 for United States Patent #7485901.
A wide bandgap semiconductor material is heavily doped to a degenerate level. Impurity densities approaching 1% of the volume of the semiconductor crystal are obtained to greatly increase conductivity. In one embodiment, a layer of AlGaN is formed on a wafer by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1.times.10.sup.20 cm.sup.-3 at Al mole fractions up to 65% are obtained.