Indium-based ohmic contacts to n-GaAs, fabricated using an ion-assisted deposition technique

The effect of simultaneously depositing In metallization on n-GaAs using a novel ion-assisted deposition (IAD) technique has been investigated. Using current-voltage, specific contact resistance and secondary ion mass spectro scopy measurements, the contacts were compared to conventional contacts fab ricated using thermal evaporation. Ion-mixed contacts fabricated with an io n close of 2.8 x 10(18) ion cm(-2) and ion energy of 1 keV exhibited a lowe r specific contact resistance of 3 x 10(-6) Omega cm(-2) at a lower anneali ng temperature of 375 degrees C compared to conventionally fabricated conta cts. For all ion doses the annealing time and temperature which gave the mi nimum specific contact resistance remained unchanged. SIMS analysis also co nfirmed that the In deposited using the ion deposition technique formed a g raded junction prior to annealing. After annealing both ion-mixed and therm ally evaporated contacts had formed the graded junction and were electrical ly comparable.