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|Title:||Effects of plasma surface treatment on ohmic contact to n-GaN|
|Authors:||Chor, E.F. |
|Citation:||Chor, E.F.,Kang, X.J. (2001). Effects of plasma surface treatment on ohmic contact to n-GaN. Materials Research Society Symposium Proceedings 680 : 184-189. ScholarBank@NUS Repository.|
|Abstract:||We have investigated the effects of plasma surface treatment on ohmic contacts to n-type GaN. Prior to metal evaporation, n-GaN surface was etched either chemically using aqua-regia (control sample) or by means of inductively coupled Cl2/BCl3, N2 or Ar plasmas. The metal system adopted in our investigation was Ti/Al/Pd/Au. The as-deposited Ti/Al/Pd/Au contact on aqua-regia treated n-GaN exhibits an ohmic behavior with a specific contact resistance (ρc) of 2×10-4 Ωcm2. After annealing at 500°C for 5min, ρc is reduced by approximately 2 orders of magnitude to 5×10 -6Ωcm2. For Cl2/BCl3 and N2 plasma treated n-GaN surface, the as-deposited Ti/Al/Pd/Au contacts also yield ohmic behavior and ρc's are about 2×10-4 and 5×10-4Ω cm2 respectively. After annealing at 500°C for 5min, ρc's are reduced by about 3 orders of magnitude to around 5×10-7 and 8×10-7Ω cm2 respectively. On the other hand, the as-deposited Ti/Al/Pd/Au contact on Ar plasma treated n-GaN exhibits a non-ohmic behavior. After annealing at 500°C for 5min, ρc is about 5×-10-7 cm2 and the lowest ρc of 7×10-8Ω cm2 is obtained after annealing at 700°C for 5min. The contacts on other surface treated n-GaN are found to degrade at 700°C annealing. By comparing the values of ρc for various surface treatments, particularly those after annealing, it is observed that plasma etching can be used beneficially in the formation of ohmic contacts - plasma surface treatment using Cl2/BCl3, N2 or Ar has resulted in an order of magnitude reduction in ρc compared to chemical surface treatment by aqua-regia. © 2001 Materials Research Society.|
|Source Title:||Materials Research Society Symposium Proceedings|
|Appears in Collections:||Staff Publications|
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