Electrical activation studies of silicon implanted Al(x)Ga(1-x)N grown on sapphire substrates were conducted as a function of ion dose, anneal temperature, and anneal time. Silicon ion doses of 1x10(exp 13), 5x10(exp 13), and 1x10(exp 14) /sq cm were implanted in Al(x)Ga(1-x)N samples with aluminum mole fractions of 0.1 and 0.2 at an energy of 200 keV at room temperature. The samples were proximity cap annealed at temperatures from 1100 to 1350 degrees C and anneal times of 20 to 40 minutes with a 500 thick AlN cap in a nitrogen environment. The Hall coefficient and resistivity were measured using room temperature Hall effect measurements. From this data the Hall mobility, sheet carrier concentration, and electrical activation efficiencies were calculated. Activation efficiencies of almost 100% were achieved for Al(0.2)Ga(0.8)N samples having doses of 5x10(exp 13) and 1x10(exp 14) /sq cm after annealing at 1350 and 1300 C, respectively, for 20 minutes. After annealing at 1250 C for 20 minutes, 87% efficiency was achieved for Al(0.1)Ga(0.9)N implanted with 1x10(exp 14) /sq cm silicon ions. The largest observed mobility was 89 /sq cm/V's for Al(0.1)Ga(0.9)N implanted with 1x10(exp 14) /sq cm and 5x10(exp 13) /sq cm silicon ions and annealed at 1250 degrees C for 20 minutes and at 1200 degrees C for 40 minutes, respectively. The optimal anneal condition to maximize electrical activation efficiency and minimize nitrogen dissociation damage for Al(0.1)Ga(0.9)N was 1200 C anneal for 40 minutes. The mobilities, sheet carrier concentrations, and electrical activation efficiencies generally increased., The original document contains color images.