WSix refractory gate metal process for GaAs MESFETs

Abstract A co-sputtering process is characterized which allows the deposition of WSi 0.4 layers for Schottky gates of GaAs self-aligned MESFETs. The process parameters were optimized to yield films with low stress, good adhesion and a high interface stability during 800°C n + implant activation anneal. The good diffusion barrier properties of the Schottky metal can be attributed to the amorphous nature of the film. This implies a natural explanation of the optimum film composition. Employing various analytical methods the gate metal/GaAs interface was characterized after 800°C anneal. I − V diode measurements were performed to obtain contact electrical properties such as barrier height and ideality factor. MESFETs with different channel implants down to 10 keV were fabricated to confirm the good stability of the Schottky contact.

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