OHMIC CONTACT TO N-TYPE AL0.71GA0.29N
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Because of its high breakdown field, wide bandgap tunability and superior heat conductivity, AlGaN has become a promising ultra-wideband gap material for high performance photonic and electronic devices. Comprehensive research on materials characteristics of AlGaN can also provide valuable insights for developing Aluminum Nitride (AlN) based devices which. Achieving ohmic contact with negligible contact resistance has been challenging in AlGaN devices, especially when Al composition becomes larger than 0.7. This thesis is intended to investigate the influence of metal stacks, surface treatments and annealing condition on contact performance of n-type Al0.71Ga0.29N. In this study, nearly ohmic I-V characteristics prior to annealing was demonstrated on heavily doped n- Al0.71Ga0.29N using both metal-first and lift-off process , which has not been previously reported in high Al composition AlGaN. Specific contact resistivity as low as 2x 10-4 Ω cm2 and 6 x 10-5 Ω cm2 are achieved separatedly n- AlGaN grown on single crystal AlN substrate . This work marks milestone in realizing superior ohmic contact for n type AlGaN , paving the way for more efficient ultra-wide bandgap electronic and optoelectronics devices.