Improved performance of GaAs MESFETs through sulfidation of Pt/GaAs interface

Sulfidation was employed to decrease defective interfacial states of Pt/GaAs Schottky contacts. With nondestructive analysis using synchrotron radiation photoemission spectroscopy, it was found that the sulfur passivation of GaAs surface prior to Pt metallization effectively reduces interfacial elemental As and As-oxides. A reduced reverse leakage current as well as enhanced barrier height was confirmed from measurements of Schottky properties. These processes were introduced to a gate junction to improve gate leakage current characteristics and pinch-off properties of GaAs metal-semiconductor field effect transistors. The leakage current was decreased by several times and the threshold voltage was lowered by the sulfidation. The results indicate that the improved device properties after the sulfidation originate in the suppression of donor-type defect like excess As at the interface. On the basis of interfacial bonding characteristics, the electrical properties could be well understood.