Low resistive ohmic contact formation on surface treated-n-GaN alloyed at low temperature
Ohmic contacts to n-type GaN with low contact resistance were developed by (NH4)2Sx and KOH+(NH4)2Sx surface treatments prior to Ti/Al metal deposition. The lowest specific contact resistance of 3.0×10−6 Ω-cm2 was obtained for Ti/Al contacts in an (NH4)2Sx-treated GaN layer alloyed at 300°C for 3 min. To obtain the lowest specific contact resistance for a low temperature alloy, the (NH4)2Sx treatment conditions for both (NH4)2Sx and KOH+(NH4)2Sx-treated n-GaN layers have been investigated and the mechanism for ohmic formation in low temperature alloys analyzed.