Silicon Ion Implant Activation in β-(Al0.2Ga0.8)2O3

As gallium oxide-based heterojunction devices gain prominence, low-resistance contacts to aluminum gallium oxide material are of increasing importance for high performance and access to modulation doped layers. Here, the activation of ion-implanted silicon donors is investigated as a function of donor density from 5 x 10(18) cm(-3) to 1 x 10(20) cm(-3), activation anneal duration from 6 s to 600 s, and activation temperature from 900 degrees C to 1140 degrees C. Importantly, ohmic behavior was achievable across a reasonably wide process window at moderate to high doping concentrations. Specific contact resistance of 1 x 10(-3) Omega cm(2) and sheet resistance of 2.8 k Omega/square were achieved for a 60 nm-deep 1 x 10(20) cm(-3) box implant after activation at 1000 degrees C for 6 s with standard Ti/Au contacts. Under these conditions, an activation efficiency of 7% was observed with Hall mobility of similar to 32 cm(2)/Vs. Furthermore, we demonstrate a Schottky diode formed of implanted material with a rectification ratio > 10(6) and further confirm the Hall carrier density results using capacitance-voltage profiling analysis. Finally, we show the significant impact of anneal duration and the potential for deleterious over-annealing which reduces the active carrier density, mobility, and resultant material conductivity.